detecting 22GHz H2O masers with a small dish

[Eduard Mol]

Hi all,

Since the successful observations of methanol masers last year I have been trying to detect water masers with my small 1 metre dish as well. Initially, I tried this with a modified Triax twin Ka band LNB, but this was not a success because the noise figure was very bad at 22.2 GHz. Recently I switched to a Norsat 9000LDF which works a lot better at 22GHz. I had to make my own feed for it, so I designed a rectangular horn antenna using the HDL-ANT program by W1GHZ and made it from a sheet of brass foil. The opening of the horn is 24X20 mm, length is 25mm. 

Recently I did some tests outside with the LNB and feedhorn mounted in the focal point of the dish. Cold sky/ ground noise was 2.9 dB at 22.2 GHz. When pointing the dish at the moon a 0.5 dB noise increase was measured. 

The LO frequency stability of the LNB was also tested by making a spectrum of a satellite beacon every few minutes for several hours. Good frequency stability was never expected because it is a DRO LNB. From the first test it appeared like the frequency drift diminished significantly when the LNB had cooled off to the temperature of the surroundings. However, a second test indicated that the frequency still drifted by about 100 KHz even after an hour. 

So the question now is: is it still possible to detect water masers with this setup despite the frequency drifting?

Best regards,

Eduard

[Eduard Mol]

Hi all,

Despite the frequency drift problem I still decided to try detecting a water maser.

On January 9 the star forming region W3 was observed for 45 minutes. A second, 3 hours long observation was carried out on January 17. I have used my earlier measurements of the Eutelsat 7A satellite beacon to correct for the LO frequency offset. There is of course still uncertainty in the frequency due to the frequency drifting of the LO. 

In the spectrum of January 9, one peak stood out at -42 km/s. There is a hint of some weaker peaks at -51 km/s and -37.5 km/s. The narrow spike at -48 km/s is an artifact of the SDR. The spectrum of January 17 has one obvious peak at -40 km/s, with possibly weaker peaks at -49 and -35.5 km/s. If these features are the same as the peaks in the spectrum of January 9, then there is a 2 km/s difference between the two spectra, possibly caused by frequency difting of the LO. 

I also averaged the two results to get a (slightly) better SNR, accounting for a possible 2 km/s shift.

Now the question is: are these bumps and peaks in the spectrum truly water masers in W3? There were two strong water maser sources in the beam of the dish: W3(OH) and W3 (2). According to maserDB (https://maserdb.net/search.pl) the water maser of W3(OH) has a Vlsr velocity of -48 to -50 km/s, and W3 (2) has a velocity of -40 to -42 km/s. The stronger peak at -40 km/s could therefore be the water maser of W3 (2), and the weaker peak around -50 km/s from W3(OH). However, these interpretations should be taken with a grain of salt since the velocities I calculated are still rather uncertain. 

Eduard.

[Wolfgang Herrmann]

Hi Eduard,

I find it more likely that the line you have at 40 km/s is actually the line from W3OH which normally would be found at 49 km/s and that the difference is due to the uncertainty in frequency. The W3OH line is significantly stronger than the W3 line. What you could do to confirm the observations is to take a recording delliberately looking "off target".

Best regards,

Wolfgang

[Eduard Mol]

Hi Wolfgang,

Thank you for your feedback. I will try wat you suggested next time when the weather improves.
Maybe I could record spectra while repeatedly pointing the dish on-target and off-target. If the line only appears when the dish is pointed on-target, then it is very likely from W3(OH)/ W3.

Best regards,

Eduard

[Eduard Mol]

Hi all,

After weeks of rain and fog we finally had some good weather yesterday. W3(OH) was at an unfavourable position in the sky (behind the house) when I had just set up my dish late in the morning, so I pointed my dish at W49 instead. 

W49 was about 40 degrees above the horizon in the southwest at that moment, well above the trees and buildings nearby. Spectra were recorded every 5 minutes. During the observation session the dish was pointed "off-target" two times (1 degree declination below and above the position of W49). "Dark" spectra for bandpass correction were recorded afterwards with the dish pointed at cold sky at an elevation of about 40 degrees. A heatmap of all the bandpass- corrected spectra recorded during the observation is shown below:

The narrow line at 22234.9 MHz is an artifact of the SDR. There is a strong line at 22235.75 MHz, which is not present in the spectra recorded off-target. This is a good indication that the line is indeed from W49. The frequency of the line shifted somewhat during the observation, probably due to frequency drifting of the LNB LO.

Finally, I averaged all the "on-target" spectra. The frequency axis was not converted to LSR velocity because of the large uncertainty in the frequency. The total integration time is about 1 hour. Besides the strong line at 22235.75 MHz there are hints of weaker lines at other frequencies as well. 

Unfortunately I could not do observations of W3(OH) because it started to rain early in the evening. I will revisit W3(OH) another time.

best regards, 

[Job Geheniau]

very nice Eduard.

Op zondag 6 februari 2022 om 16:21:56 UTC+1 schreef eddiem...@gmail.com:

[fasleitung3]

Very nice observation, Eduard.

It is very impressive that this was done with a 1-m dish!

Wolfgang

[Michiel Klaassen]

Hi Eduard,

Wow;a nice result again, and no doubt that this is the source.

Congrats,

Michiel

parac.eu

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[Marcus D. Leech]

On 2022-02-06 10:21, Eduard Mol wrote:

Hi all,

After weeks of rain and fog we finally had some good weather yesterday. W3(OH) was at an unfavourable position in the sky (behind the house) when I had just set up my dish late in the morning, so I pointed my dish at W49 instead. 

W49 was about 40 degrees above the horizon in the southwest at that moment, well above the trees and buildings nearby. Spectra were recorded every 5 minutes. During the observation session the dish was pointed "off-target" two times (1 degree declination below and above the position of W49). "Dark" spectra for bandpass correction were recorded afterwards with the dish pointed at cold sky at an elevation of about 40 degrees. A heatmap of all the bandpass- corrected spectra recorded during the observation is shown below:

The narrow line at 22234.9 MHz is an artifact of the SDR. There is a strong line at 22235.75 MHz, which is not present in the spectra recorded off-target. This is a good indication that the line is indeed from W49. The frequency of the line shifted somewhat during the observation, probably due to frequency drifting of the LNB LO.

Finally, I averaged all the "on-target" spectra. The frequency axis was not converted to LSR velocity because of the large uncertainty in the frequency. The total integration time is about 1 hour. Besides the strong line at 22235.75 MHz there are hints of weaker lines at other frequencies as well. 

Unfortunately I could not do observations of W3(OH) because it started to rain early in the evening. I will revisit W3(OH) another time.

best regards, 

Eduard

Could you remind us of which LNB you're using, and whether you had to modify it?

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[eddiem...@gmail.com]

Hi Marcus,

I am using a Norsat 9000LD Ka band DRO LNB. It is not modified.

Best regards,

Eduard 

Op 6 feb. 2022 om 20:54 heeft Marcus D. Leech <patchv...@gmail.com> het volgende geschreven:



To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/fda8dacd-d910-1846-870d-f4a6d14497d8%40gmail.com.

[Eduard Mol]

Today I pointed my dish at yet another star forming region: W51. A strong flare of the 22.2 GHz maser in this star forming region was reported in October 2021,  it reached a flux density of 26200 Jy. (see ATel #15002: https://www.astronomerstelegram.org/?read=15002). the W51 water maser is therefore one of the most promising targets for detection with a small dish, especially if the flare is still going on right now.

Like during the observations of W49 last saturday, I pointed the dish 1 degree away from the target twice during the observation session. A strong line was detected at 22231.75 MHz, which was absent when the dish was pointed 1 degree away from the target. Towards the end of the observing session I noticed that the pointing was off by about 25 arcminutes, so I adjusted the position of the dish  until the signal was at maximum strength. Despite the fact that the pointing was somewhat off during most of the observation session, the SNR is still much better than expected.

I had to stop my observations late in the afternoon due to the weather, so W3(OH) will have to wait for another time again...

Best regards,

Eduard

[Job Geheniau]

Nice Ed!

Short question,

Where do you get the 'objects' you want to observe?

Job

Op maandag 7 februari 2022 om 21:57:33 UTC+1 schreef eddiem...@gmail.com:

[Eduard Mol]

Hi Job,

For target selection I used the Arcetri H2O maser catalog by Valdettaro et al. (2001), available on VizieR (https://vizier.cds.unistra.fr/viz-bin/VizieR-3?-source=J/A%2bA/368/845&-out.max=50&-out.form=HTML%20Table&-out.add=_r&-out.add=_RAJ,_DEJ&-sort=_r&-oc.form=sexa), and the search tool of the maser database MaserDB (https://maserdb.net/). However, water masers are highly variable over timescales of a few months to years, so the reported flux densities should be taken with some caution especially if the observations were done many years ago. 

[Job Geheniau]

Thanks!

Op 8 feb. 2022 om 16:37 heeft Eduard Mol <eddiem...@gmail.com> het volgende geschreven:

Hi Job,

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[Eduard Mol]

Hi all,

Last weekend I observed W3(OH) and another water maser source: Orion KL. 

Here are the results from W3(OH):

As can be seen the relatively strong peak at 22236 MHz disappeared when the dish was pointed away from the source. This is a good indication that W3(OH) is indeed detected.

Orion KL, a strong maser source inside the well-known Orion nebula, was also detected:

Besides the stronger signal at 22229.7 MHz there seem to be multiple weaker lines from this source. 

I did notice that bandpass correction is very tricky, the spectra of W3(OH) and Orion KL shown here are not very flat. This is possibly due to varying amounts of water vapour in the telescope beam when it is tracking objects in the sky. 

[vk3...@gmail.com]

Excellent work Eduard…really impressed.

 

Do you have any information on what you are using for 22.2 GHz receiver?

 

Cheers

Clint Jeffrey – VK3CSJ

ASV-RAS

 

From: sara...@googlegroups.com <sara...@googlegroups.com> On Behalf Of Eduard Mol
Sent: Tuesday, 15 February 2022 7:16 AM
To: Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Subject: Re: [SARA] Re: detecting 22GHz H2O masers with a small dish

 

Hi all,

 

Last weekend I observed W3(OH) and another water maser source: Orion KL. 

 

Here are the results from W3(OH):

As can be seen the relatively strong peak at 22236 MHz disappeared when the dish was pointed away from the source. This is a good indication that W3(OH) is indeed detected.

 

Orion KL, a strong maser source inside the well-known Orion nebula, was also detected:

Besides the stronger signal at 22229.7 MHz there seem to be multiple weaker lines from this source. 

I did notice that bandpass correction is very tricky, the spectra of W3(OH) and Orion KL shown here are not very flat. This is possibly due to varying amounts of water vapour in the telescope beam when it is tracking objects in the sky. 

 

 

 

 

 

 

On Tuesday, 8 February 2022 at 17:12:46 UTC+1 jobge...@gmail.com wrote:

Thanks!

Op 8 feb. 2022 om 16:37 heeft Eduard Mol <eddiem...@gmail.com> het volgende geschreven:

Hi Job,

 

For target selection I used the Arcetri H2O maser catalog by Valdettaro et al. (2001), available on VizieR (https://vizier.cds.unistra.fr/viz-bin/VizieR-3?-source=J/A%2bA/368/845&-out.max=50&-out.form=HTML%20Table&-out.add=_r&-out.add=_RAJ,_DEJ&-sort=_r&-oc.form=sexa), and the search tool of the maser database MaserDB (https://maserdb.net/). However, water masers are highly variable over timescales of a few months to years, so the reported flux densities should be taken with some caution especially if the observations were done many years ago. 

 

On Monday, 7 February 2022 at 22:33:53 UTC+1 jobge...@gmail.com wrote:

Nice Ed!

 

Short question,

 

Where do you get the 'objects' you want to observe?

 

Job

Op maandag 7 februari 2022 om 21:57:33 UTC+1 schreef eddiem...@gmail.com:

Today I pointed my dish at yet another star forming region: W51. A strong flare of the 22.2 GHz maser in this star forming region was reported in October 2021,  it reached a flux density of 26200 Jy. (see ATel #15002: https://www.astronomerstelegram.org/?read=15002). the W51 water maser is therefore one of the most promising targets for detection with a small dish, especially if the flare is still going on right now.

 

Like during the observations of W49 last saturday, I pointed the dish 1 degree away from the target twice during the observation session. A strong line was detected at 22231.75 MHz, which was absent when the dish was pointed 1 degree away from the target. Towards the end of the observing session I noticed that the pointing was off by about 25 arcminutes, so I adjusted the position of the dish  until the signal was at maximum strength. Despite the fact that the pointing was somewhat off during most of the observation session, the SNR is still much better than expected.

I had to stop my observations late in the afternoon due to the weather, so W3(OH) will have to wait for another time again...

 

Best regards,

 

Eduard

 

On Sunday, 6 February 2022 at 21:06:53 UTC+1 Eduard Mol wrote:

Hi Marcus,

I am using a Norsat 9000LD Ka band DRO LNB. It is not modified.

 

Best regards,

Eduard 

 

Op 6 feb. 2022 om 20:54 heeft Marcus D. Leech <patchv...@gmail.com> het volgende geschreven:



On 2022-02-06 10:21, Eduard Mol wrote:

Hi all,

 

After weeks of rain and fog we finally had some good weather yesterday. W3(OH) was at an unfavourable position in the sky (behind the house) when I had just set up my dish late in the morning, so I pointed my dish at W49 instead. 

W49 was about 40 degrees above the horizon in the southwest at that moment, well above the trees and buildings nearby. Spectra were recorded every 5 minutes. During the observation session the dish was pointed "off-target" two times (1 degree declination below and above the position of W49). "Dark" spectra for bandpass correction were recorded afterwards with the dish pointed at cold sky at an elevation of about 40 degrees. A heatmap of all the bandpass- corrected spectra recorded during the observation is shown below:

The narrow line at 22234.9 MHz is an artifact of the SDR. There is a strong line at 22235.75 MHz, which is not present in the spectra recorded off-target. This is a good indication that the line is indeed from W49. The frequency of the line shifted somewhat during the observation, probably due to frequency drifting of the LNB LO.

 

Finally, I averaged all the "on-target" spectra. The frequency axis was not converted to LSR velocity because of the large uncertainty in the frequency. The total integration time is about 1 hour. Besides the strong line at 22235.75 MHz there are hints of weaker lines at other frequencies as well. 

 

Unfortunately I could not do observations of W3(OH) because it started to rain early in the evening. I will revisit W3(OH) another time.

 

best regards, 

Eduard

 

Could you remind us of which LNB you're using, and whether you had to modify it?

On Thursday, 20 January 2022 at 17:51:26 UTC+1 Eduard Mol wrote:

Hi Wolfgang,

 

Thank you for your feedback. I will try wat you suggested next time when the weather improves.
Maybe I could record spectra while repeatedly pointing the dish on-target and off-target. If the line only appears when the dish is pointed on-target, then it is very likely from W3(OH)/ W3.

Best regards,

Eduard

On Thursday, 20 January 2022 at 17:26:15 UTC+1 Wolfgang Herrmann wrote:

Hi Eduard,

I find it more likely that the line you have at 40 km/s is actually the line from W3OH which normally would be found at 49 km/s and that the difference is due to the uncertainty in frequency. The W3OH line is significantly stronger than the W3 line. What you could do to confirm the observations is to take a recording delliberately looking "off target".

Best regards,

Wolfgang

 

 

eddiem...@gmail.com schrieb am Mittwoch, 19. Januar 2022 um 20:44:20 UTC+1:

Hi all,

 

Despite the frequency drift problem I still decided to try detecting a water maser.

On January 9 the star forming region W3 was observed for 45 minutes. A second, 3 hours long observation was carried out on January 17. I have used my earlier measurements of the Eutelsat 7A satellite beacon to correct for the LO frequency offset. There is of course still uncertainty in the frequency due to the frequency drifting of the LO. 

 

In the spectrum of January 9, one peak stood out at -42 km/s. There is a hint of some weaker peaks at -51 km/s and -37.5 km/s. The narrow spike at -48 km/s is an artifact of the SDR. The spectrum of January 17 has one obvious peak at -40 km/s, with possibly weaker peaks at -49 and -35.5 km/s. If these features are the same as the peaks in the spectrum of January 9, then there is a 2 km/s difference between the two spectra, possibly caused by frequency difting of the LO. 

I also averaged the two results to get a (slightly) better SNR, accounting for a possible 2 km/s shift.

To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/63e519ca-161e-4148-a40d-398badf473a0n%40googlegroups.com.

[eddiem...@gmail.com]

Hi,

I am using a Norsat 9000LDF LNB and a Nooelec NeSDR XTR SDR receiver, see also the first post in this thread.

Best regards,

Eduard

Op 15 feb. 2022 om 14:18 heeft vk3...@gmail.com het volgende geschreven:



To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/063501d8226e%2478faf810%246af0e830%24%40gmail.com.

[Eduard Mol]

Hi all,

Over the last few weeks I have done more observations at 22 GHz. The dish has been pointed at W75, Cepheus A, NGC 2071, NGC 7129, IRAS 06053-0622 and G25.8-0.18. None of these sources have been detected so far: these are probably too weak at the moment for detection with my small 1-metre dish. 

W49 and W51 have been successfully observed again lately. It seems that the spectrum of both sources has changed since my earlier observations 5 to 6 weeks ago. Note that the vertical axis has not been calibrated; it is therefore unclear what part of the observed changes is due to intrinsic variability of the source, and what part is due to gain variation, pointing errors or differences in air humidity. However, pointing errors and gain variations should affect all the maser features in the spectrum equally. When the spectra of W49 taken on February 13 and March 26 are compared, the intensity of the strongest peak has clearly decreased while the weaker peaks have remained mostly the same. It is therefore likely that the decrease of the highest peak is (mostly) due to intrinsic variability of the source.

The brightness of W51 seems to have dropped even more. On the other hand the spectrum of W51 lacks other sufficiently strong features to compare with, so it is hard to say what part (if at all) of the observed change is real.

Anyway, it would be interesting to observe these sources again in a month or so. It would also be nice to find some way to calibrate both the frequency and vertical axis.

[Eduard Mol]

Hi all,

It has been a month since the last observations, so I decided it was time to check W49 and W51 again. 

Like last month, the new observations were plotted over the earlier spectra. Since I still have no method to calibrate the frequency I just aligned the peaks. This is obviously not a great solution, so somewhere in the next few months we will try to generate a reference signal to correct for the frequency drift and offset. 

The main peak and some of the weaker peaks of W49 seem to have become stronger. However, it is unclear whether this increase is real or just a result of better observing conditions. On the other hand, it can be seen that the intensity of the peaks with respect to each other varies as well, which suggests that these changes are at least partially due to the intrinsic variability of the maser. 

The intensity of W51 seems to have dropped even further since last month. It seems unlikely that such a large (>10 fold) intensity change is simply a result of different observing conditions (e.g. temperature or moisture) or pointing, given that I always get roughly the same values when I point the dish at the sun or W49.

 

Actually calibrating my measurements to Jansky is probably very difficult, because absorbtion and higher sky temperature (due to water vapour in the atmosphere) has to be taken into account. If anyone has suggestions please feel free to let me know :-)

Best regards,

Eduard

[Job Geheniau]

Nice results again Eduard.

Op 30 apr. 2022 om 21:12 heeft Eduard Mol <eddiem...@gmail.com> het volgende geschreven:

Hi all,

It has been a month since the last observations, so I decided it was time to check W49 and W51 again. 

Like last month, the new observations were plotted over the earlier spectra. Since I still have no method to calibrate the frequency I just aligned the peaks. This is obviously not a great solution, so somewhere in the next few months we will try to generate a reference signal to correct for the frequency drift and offset. 

The main peak and some of the weaker peaks of W49 seem to have become stronger. However, it is unclear whether this increase is real or just a result of better observing conditions. On the other hand, it can be seen that the intensity of the peaks with respect to each other varies as well, which suggests that these changes are at least partially due to the intrinsic variability of the maser. 

<W49_22GHz_3.png>

<W49_22GHz_2704.png>

The intensity of W51 seems to have dropped even further since last month. It seems unlikely that such a large (>10 fold) intensity change is simply a result of different observing conditions (e.g. temperature or moisture) or pointing, given that I always get roughly the same values when I point the dish at the sun or W49.

<W51_0222_0422a.png>

 

<W51_300422_spectrum.png>

To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/0cf28d01-c175-46a7-ab5e-bfe2f4374a1an%40googlegroups.com.

<W51_0222_0422a.png>

<W49_22GHz_2704.png>

<W49_22GHz_3.png>

<W51_300422_spectrum.png>

[Eduard Mol]

Hi all,

As mentioned in my post in Michiels thread on W49 yesterday I have been working on a reference signal. In this post I will share some of the details and results on this part of the project.

Recently I ordered a Leo Bodnar GPSDO. The output of this GPSDO is not a very "clean" signal, it has lots of harmonics at higher frequency. Now this was actually quite desirable for my project: when I attached a crude homemade 13.5mm dipole antenna to the output and set the GPSDO frequency output to 794.107143 MHz, I could detect the 28th harmonic at 22235 MHz!. The signal was of course very weak, but that was just wat I needed. However, I did not want this setup to generate lots of RFI at lower frequencies, so I built a small circular waveguide from a piece of 1cm copper tube. The inner diameter is 8mm, so the cutoff frequency should be around 11 GHz. In order to make this small antenna more directional I added a conical horn section with an opening of 35mm. 

With this mounted on the dish I could finally generate a reference signal, which can be used for correcting the frequency drift and offset of the LNB

Now it is also possible to do LSR correction, which I did for my most recent observations of W49 and W51 (on May 28 and June 2 respectively). 

For comparison I tried to plot my earlier observations of W49 and W51 on the Vlsr scale of my most recent observations. This was of course mostly guesswork, trying to match the peaks.

It can be seen that the broad peak at around -6km/s in the spectrum of W49 has clearly increased in intensity compared to the narrower peak at +5.5km/s W51 on the other hand  does not seem to have changed very much since last month. 

To be continued...

Eduard

[Eduard Mol]

Hi all, 

A few days ago Michiel Klaassen posted a 12 MHz wide spectrum of W49 over on the CAMRAS forum. Some masing clouds inside the W49 star forming region move at very high velocity, and their emission lines are therefore shifted by several MHz. The bandwidth of the SDRs Michiel and I use is limited to 2.5 MHz, so we often miss some of the highly red- and blueshifted peaks. To make a wider spectrum Michiel made a script for frequency-hopping, essentially taking several spectra at 2 MHz intervals and adding them together. Yesterday Itried something similar, making a 12 MHz wide spectrum composed of six spectra at 2 MHz intervals with 10 minutes integration time each. 

The strongest emission is between -10 and +20 km/s, which is the part I have made spectra of before. However, there are several weaker peaks at -43, -41, -18, +22 and +58 km/s.

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[Eduard Mol]

Hi all, 

A few nights ago I made a new spectrum of W51. It seems that this maser has not changed that much over the last few months.

Because the graphs with all the spectra plotted over each other are getting rather messy, I experimented with some other ways to visualise all the spectra collected in the last few months. One option is to make "stacking graphs". The shape of the peaks is nicely visible in this type of graph However, changes in the weaker peaks are not so easy to see, while the stronger peaks still overlap.

It is also possible to plot a "heatmap"-type graph, which has the intensity represented as a colour. What I like about this type of diagram is that changes in the peaks are very well displayed. On the other hand, the shape of the peaks is not well represented. To summarize, each type of graph has its own pro's and con's...

[Steve Olney]

Hi Eduard,

I've done an 'unroll' of your excellent series of posts about detecting H2O masers with a small dish.  I used Latex to generate a PDF.  I did it for my own reference - but perhaps you might be interested to have a look ?  Let me know if you do and I will put it in the cloud and send a link.

Cheers Steve (HawkRAO)

[Clint Jeffrey]

This is amazing work by Eduard, unless I missed the email is there a write up of Eduard setup, I gather he’s using a small dish but that’s about all that is revealed in his posts below. Would be interested in some tech info on his 22.2 GHz receiver.

 

Cheers

Clint Jeffrey – VK3CSJ

 

Sent from Mail for Windows

 

From: Steve Olney
Sent: Friday, 26 August 2022 10:09 AM
To: Society of Amateur Radio Astronomers
Subject: Re: [SARA] Re: detecting 22GHz H2O masers with a small dish

 

Hi Eduard,

 

I've done an 'unroll' of your excellent series of posts about detecting H2O masers with a small dish.  I used Latex to generate a PDF.  I did it for my own reference - but perhaps you might be interested to have a look ?  Let me know if you do and I will put it in the cloud and send a link.

 

Cheers Steve (HawkRAO)

On Thursday, August 11, 2022 at 3:06:51 AM UTC+10 eddiem...@gmail.com wrote:

Hi all, 

 

A few nights ago I made a new spectrum of W51. It seems that this maser has not changed that much over the last few months.

 

Because the graphs with all the spectra plotted over each other are getting rather messy, I experimented with some other ways to visualise all the spectra collected in the last few months. One option is to make "stacking graphs". The shape of the peaks is nicely visible in this type of graph However, changes in the weaker peaks are not so easy to see, while the stronger peaks still overlap.

It is also possible to plot a "heatmap"-type graph, which has the intensity represented as a colour. What I like about this type of diagram is that changes in the peaks are very well displayed. On the other hand, the shape of the peaks is not well represented. To summarize, each type of graph has its own pro's and con's..

 

 

On Sun, 7 Aug 2022 at 12:22, Eduard Mol <eddiem...@gmail.com> wrote:

Hi all, 

 

A few days ago Michiel Klaassen posted a 12 MHz wide spectrum of W49 over on the CAMRAS forum. Some masing clouds inside the W49 star forming region move at very high velocity, and their emission lines are therefore shifted by several MHz. The bandwidth of the SDRs Michiel and I use is limited to 2.5 MHz, so we often miss some of the highly red- and blueshifted peaks. To make a wider spectrum Michiel made a script for frequency-hopping, essentially taking several spectra at 2 MHz intervals and adding them together. Yesterday Itried something similar, making a 12 MHz wide spectrum composed of six spectra at 2 MHz intervals with 10 minutes integration time each. 

The strongest emission is between -10 and +20 km/s, which is the part I have made spectra of before. However, there are several weaker peaks at -43, -41, -18, +22 and +58 km/s.

 

 

 

On Thu, 2 Jun 2022 at 21:42, Eduard Mol <eddiem...@gmail.com> wrote:

Hi all,

 

As mentioned in my post in Michiels thread on W49 yesterday I have been working on a reference signal. In this post I will share some of the details and results on this part of the project.

Recently I ordered a Leo Bodnar GPSDO. The output of this GPSDO is not a very "clean" signal, it has lots of harmonics at higher frequency. Now this was actually quite desirable for my project: when I attached a crude homemade 13.5mm dipole antenna to the output and set the GPSDO frequency output to 794.107143 MHz, I could detect the 28th harmonic at 22235 MHz!. The signal was of course very weak, but that was just wat I needed. However, I did not want this setup to generate lots of RFI at lower frequencies, so I built a small circular waveguide from a piece of 1cm copper tube. The inner diameter is 8mm, so the cutoff frequency should be around 11 GHz. In order to make this small antenna more directional I added a conical horn section with an opening of 35mm. 

With this mounted on the dish I could finally generate a reference signal, which can be used for correcting the frequency drift and offset of the LNB

Now it is also possible to do LSR correction, which I did for my most recent observations of W49 and W51 (on May 28 and June 2 respectively). 

For comparison I tried to plot my earlier observations of W49 and W51 on the Vlsr scale of my most recent observations. This was of course mostly guesswork, trying to match the peaks.

It can be seen that the broad peak at around -6km/s in the spectrum of W49 has clearly increased in intensity compared to the narrower peak at +5.5km/s W51 on the other hand  does not seem to have changed very much since last month. 

 

To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/6ddc8f34-d694-456b-84a6-fc9532b2e7c6n%40googlegroups.com.

 

[Marcus D. Leech]

On 2022-08-25 20:33, Clint Jeffrey wrote:

This is amazing work by Eduard, unless I missed the email is there a write up of Eduard setup, I gather he’s using a small dish but that’s about all that is revealed in his posts below. Would be interested in some tech info on his 22.2 GHz receiver.

 

Cheers

Clint Jeffrey – VK3CSJ

 

Our 12.8m dish has a surface that would likely work more-than-adequately for doing this type of work.  The issue is that
  there's no way we could point accurately enough anytime soon--until our Uni partners cough up $$ for better sensors.
  But the surface is good to about 1mm RMS--at least it was at time of installation.  Even if it has "drifted" a 12.8m dish
  with only 30% efficiency would still be tremendous...

But for now, I'm fighting gremlins at 21cm...

To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/6D71F7AE-17D7-4A74-A757-214EFF6E9345%40hxcore.ol.

[Steve Olney]

Hi Clint - I think all the required info is in Eduard's posts - which is why I did an 'unroll'.   A great reference for myself as in the next 5 to 10 years we will need to 'downsize' and I have been pondering what could be done in a limited space.   I reckon a 1m dish would be OK then.

Cheers

Steve (HawkRAO)

[Clint Jeffrey]

G’day Steve...good to hear from you. Yes agree with your “unroll” as you say, which makes sense to me too.

 

Apart from the various charts and plots the only thing I see of technical value is the signal source he used for generating a reference. I was wondering if Eduard may have described the 22.2 GHz receiver arrangement, I read a reference to an SDR being used but there must be a Down Converter of some sort also being employed at the focal point, I would imagine...;)

 

Clint...

 

Sent from Mail for Windows

 

From: Steve Olney
Sent: Friday, 26 August 2022 11:25 AM
To: Society of Amateur Radio Astronomers
Subject: Re: [SARA] Re: detecting 22GHz H2O masers with a small dish

 

Hi Clint - I think all the required info is in Eduard's posts - which is why I did an 'unroll'.   A great reference for myself as in the next 5 to 10 years we will need to 'downsize' and I have been pondering what could be done in a limited space.   I reckon a 1m dish would be OK then.

 

Cheers

Steve (HawkRAO)

 

 

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[Steve Olney]

Hi Clint - G'day - the details of the LNB and the SDR used to receive the IF are in the 'unroll'.  I also tracked down the datasheet for the LNB.

If Eduard gives permission I will post a link here to the 'unroll' PDF.

Cheers

Steve (HawkRAO)

[Eduard Mol]

G'day Steve, 

Yes- feel free to post a link to your "unroll" document- I can also use it later on as a basis for more comprehensive documentation of this project. The technical details are there but they are a bit scattered in this thread. I have also written a short article for the July- August SARA journal. 

Best regards,

Eduard

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[Clint Jeffrey]

Thanks Eduard....just found your article in the SARA Newsletter...all is explained...;)

 

Cheers...and great work!

 

Clint – VK3CSJ

Melbourne

 

Sent from Mail for Windows

 

From: Eduard Mol
Sent: Friday, 26 August 2022 5:23 PM
To: sara...@googlegroups.com
Subject: Re: [SARA] Re: detecting 22GHz H2O masers with a small dish

 

G'day Steve, 

To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/CAFcm1Q7ekb%3D22hxy0UDY%3DZkXmjCck3%3DtCG3GsHHMkDKfoMYo9w%40mail.gmail.com.

 

[Steve Olney]

Hi Eduard,

Email me at...

pul...@joataman.net

..and I'll send you the link to see if you think all is OK.

Or I can post the link here before you OK it.

Steve

[Steve Olney]

Here is the link to an 'unroll' of Eduard's excellent series of posts...

https://www.dropbox.com/s/zo5u43616trrttt/DETECTING_H2O_MASERS_WITH_A_SMALL_DISH.pdf?dl=0

Cheers

Steve (HawkRAO)

[Eduard Mol]

Hi all,

In the last few weeks I did quite a few observation projects, and in this post I will share the results.

First of all, I tried to detect OH 43.8-0.13, but unfortunately the result was negative. This maser is probably not strong enough at the moment. 

The source W75 was successfully detected with 80 minutes of integration time. My earlier attempt to detect it in March was unsuccessful, so the maser must have become stronger since then.

I attempted to detect IRAS 18316-0602 on the evenings of August 29 and 31 and September 2. Shown below is the averaged spectrum from these three observing sessions, the total integration time is about five and a half hours. It seems that this source is rather weak at the moment. A small peak was detected near the expected velocity of 42.5 km/s, but this peak is just barely above the noise and right next to the "dip" from the central spike of the SDR spectrum. I therefore suspect that it may just be an artifact.

Finally, a driftscan of W49 was made. Despite the short integration time (3 minutes) W49 was clearly detected. It should therefore be possible to detect the strongest water masers (or atleast W49) without a tracking mount. The SNR could be improved by averaging the results from multiple transits.

Best regards,

Eduard

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[Dennis Spender]

Please forgive me for such a juvenile question as this; I’m new to the list and topic of RA. What is a maser? Reading the posts I get the sense it is a general term for a characteristic of cosmic atoms you are searching for. 

Dennis 

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[Stephen Thornber]

I too am new and no question is juvenile!

And I would like to know this. 

Stephen G6SGA 

Sent from my iPhone

On 03 Sep 2022, at 13:45, Dennis Spender <dwsp...@gmail.com> wrote:



Please forgive me for such a juvenile question as this; I’m new to the list and topic of RA. What is a maser? Reading the posts I get the sense it is a general term for a characteristic of cosmic atoms you are searching for. 

Dennis 

On Sat, Sep 3, 2022 at 7:27 AM Eduard Mol <eddiem...@gmail.com> wrote:

Hi all,

In the last few weeks I did quite a few observation projects, and in this post I will share the results.

First of all, I tried to detect OH 43.8-0.13, but unfortunately the result was negative. This maser is probably not strong enough at the moment. 

The source W75 was successfully detected with 80 minutes of integration time. My earlier attempt to detect it in March was unsuccessful, so the maser must have become stronger since then.

<W75_230822x.png>

I attempted to detect IRAS 18316-0602 on the evenings of August 29 and 31 and September 2. Shown below is the averaged spectrum from these three observing sessions, the total integration time is about five and a half hours. It seems that this source is rather weak at the moment. A small peak was detected near the expected velocity of 42.5 km/s, but this peak is just barely above the noise and right next to the "dip" from the central spike of the SDR spectrum. I therefore suspect that it may just be an artifact.

<G25possiblesignal.png>

Finally, a driftscan of W49 was made. Despite the short integration time (3 minutes) W49 was clearly detected. It should therefore be possible to detect the strongest water masers (or atleast W49) without a tracking mount. The SNR could be improved by averaging the results from multiple transits.

<W49driftscanplot1.png>

<W49driftresult1.png>

Best regards,

Eduard

To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/CAG%3DXrMxGdfQjYZDvVtiMyhyEFDXUnCW6%2BLL45QXgOtZ5W9aaRQ%40mail.gmail.com.

[fasleitung3]

A maser is in principle the same as a laser, albeit in the microwave regime. It can occur naturally in space under certain cirumstances.

https://en.wikipedia.org/wiki/Astrophysical_maser

Wolfgang

[fasleitung3]

Am Samstag, den 03.09.2022, 13:27 +0200 schrieb Eduard Mol:

Finally, a driftscan of W49 was made. Despite the short integration time (3 minutes) W49 was clearly detected. It should therefore be possible to detect the strongest water masers (or atleast W49) without a tracking mount. The SNR could be improved by averaging the results from multiple transits.

Best regards,

Eduard

Eduard,

could it be possible that this spectrum is shifted by ~5 km/s to the left (i.e. to the blue). The reason I am asking is that I had a look at a spectrum I recorded back in January of 2019 where the main peak was at 10km/s with a broad emission around 0 km/s. This basic structure looks like yours but being 5 km/s further to the right.

Of course, given the high variablilty of these masers the shift may be intrinsic to the source.

Impressive result!

Wolfgang

[Dennis Spender]

Are we stimulating this maser emission and then measuring it or is some natural phenomenon stimulating it and then we measure it?

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[Eduard Mol]

Hi Wolfgang,

The W49 spectrum made by Michiel is almost the same as mine, with a strong narrow peak at +5 km/s and broader, weaker emission between -10 and +15 km/s. I do not think there is a 5 km/s velocity error since both Michiel and I are using a GPSDO frequency standard. I have seen changes in the spectrum over the past 6 months, so I think the difference between your spectrum from 2019 and my recent spectra may well be due to the intrinsic variability of the source.

Op za 3 sep. 2022 om 14:15 schreef 'fasleitung3' via Society of Amateur Radio Astronomers <sara...@googlegroups.com>

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[Eduard Mol]

Hello Dennis,

These masers are naturally stimulated by strong infrared radiation or collisions between the gas molecules. That is also why we find these masers in star forming regions: plenty of IR radiation and shockwaves from protostars there.

Op za 3 sep. 2022 om 14:15 schreef Dennis Spender <dwsp...@gmail.com>

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[Dennis Spender]

Great. Thanks. 

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[Marcus D. Leech]

On 2022-09-03 08:53, Dennis Spender wrote:

Great. Thanks.

There are a bunch of astronomical maser lines, including two different lines caused by Methanol masering--again mostly
  in star-forming regions, and pumped by ultraviolet as far as I know.

In addition to maser lines, there are an extensive pantheon of emission lines created by all kinds of  physics both
  in molecules and individual atoms.   Many of them are too weak to be observed by an amateur observatory, but some
  of them, most notably neutral hydrogen, are quite bright.

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[fasleitung3]

Thanks Eduard,

then it seems to be intrinsic to the source. I am reasonably confident that our measurement was accurate with respect to the velocity as it was referenced to our observatory master clock which is rubidium based. It is not surprising anyway as these source can be quite variable.

Unfortunately I cannot do observations in this band right now as our 10-m dish is configured for 10 GHz EME at the moment.

Good luck with further observations,

Wolfgang

[Dimitry UA3AVR]

Congrats, Eduard ... 

Is it possible to estimate the flux of detected masers? The small dish and 3 min of the integration time tell that the peak of W49 could be rather high.

суббота, 3 сентября 2022 г. в 17:32:27 UTC+3, Wolfgang Herrmann:

[Captain Anne Flint]

Hi Eduard, 

I’m in the midst of your interesting maser article published in the SARA newsletter. 

Thanks, 

Wende 

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[Dimitry UA3AVR]

Thanks, Eduard ...

>>Is it possible to estimate the flux of detected masers? 

>>The small dish and 3 min of the integration time 

>>tell that the peak of W49 could be rather high.

Already found the data in your recent paper. Really strong, but significant variability.

суббота, 3 сентября 2022 г. в 23:30:30 UTC+3, bera...@gmail.com:

[Eduard Mol]

Hi Dimitry,

For some reason I could not access maserDB today, maybe it is temporarily offline, but if I remember correctly the flux densities reported there were in the order of thousands to tens of thousands Jansky. 

Actually determining the flux density from my own measurements is difficult, because I have no calibration source and variations in the amount of water vapor in the atmosphere have to be accounted for. I did make a rough guesstimate of the flux of W49 from my own measurements, which was around 26000 Jy, so quite strong indeed.

Op za 3 sep. 2022 om 21:14 schreef Dimitry UA3AVR <ua3avr...@gmail.com>

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[Dimitry UA3AVR]

OK, Eduard, thanks ... 

... a rough estimate is what of needed to know detection chances (and keeping in mind the variability). The maser DB is already accessible again.

воскресенье, 4 сентября 2022 г. в 23:15:47 UTC+3, eddiem...@gmail.com:

[Eduard Mol]

Hi all,

Last night I observed the W3 region again. There are two water maser sources in this region; W3(OH) and W3(2). W3(OH) is usually the strongest of the two. MaserDB lists LSR velocities of -48 to -50 km/s for the main peak of W3(OH) and -35 to -41 km/s for W3(2). Last winter I already did some observations of W3, but since I had no frequency reference it was not possible to calculate LSR velocities and figure out whether the detected lines belonged to W3(OH) or W3(2). 

I just processed the data from last night's observation session, and to my surprise there is no signal at the expected velocity of W3(OH). Instead, there are three peaks at -37, -39 and -41 km/s, which is more consistent with W3(2). Alternatively, the frequency correction or LSR correction could be off. However, W51m was observed as well yesterday as part of my W49/ W51 monthly observation program, and the peak velocity of 58 km/s is consistent with my earlier observations and with the LSR velocities listed in maserDB. So a mistake in the frequency or velocity correction seems less likely. I will try to repeat my observations later this month to see what is going on here...

Eduard

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[Dimitry UA3AVR]

Well done, Eduard, congrats! I did note the W3(OH) object emits the H20 radiation too. Hope to see these line in future.

воскресенье, 9 октября 2022 г. в 13:00:16 UTC+3, eddiem...@gmail.com:

[Eduard Mol]

Hi all,

Last week the water maser in the star forming region Cepheus A was successfully observed. The first successful observation was done on the evening of October 9. Two weak peaks were detected very close to the expected LSR velocity of -10 km/s. The integration time was approximately 60 minutes. The observation was repeated on October 10; this time the peaks were a bit stronger and the SNR was better as well. This could be due to better observing conditions or more accurate pointing.

Cepheus A is the sixth water maser source observed with the 1- metre "mini maser telescope", the other sources are W49, W51, W3, Orion KL and W75N. It seems that there are more than a few sources detectable at 22.2 GHz with relatively modest equipment.

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[Anthony]

Hi Eduard,

Congratulations! I may have asked this before and pardon me if I have, what type of LNA, BPF, are you using?

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[Job Geheniau]

Eduard,

Mooie resultaten.

Ik vind het prachtig om te zien hoe wij als amateurs het uiterste vergen van de apparatuur waarmee wij werken!

Fijne hobby ondanks dat de hardware (mijnerzijds momenteel) het soms laat afweten. Opgeven is geen optie :-).  !

Gefeliciteerd!

We houden contact en ik kom gaar op (korte) termijn langs om eens een meting te doen met jouw apparatuur wat betreft mijn Nooelec SmartSDR.

Groet Job

Eduard,

Nice results.
I love to see how we as amateurs push the limits of the equipment we work with!
Fine hobby despite the hardware (for my part currently) sometimes failing. Giving up is not an option :-).  !

Congratulations!!!

We'll keep in touch and I'll drop by in the (short) term to do a measurement with your equipment regarding my Nooelec SmartSDR.

Greetings Job

Op zondag 16 oktober 2022 om 21:34:51 UTC+2 schreef eddiem...@gmail.com:

[Dimitry Fedorov]

My cograts also, Eduard! Is there any information about physics beyond the two peak spectrum? Why the line is splitted, Zeeman effect or something else?

regards, Dimitry UA3AVR

вс, 16 окт. 2022 г., 23:23 Job Geheniau <jobge...@gmail.com>:

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[Eduard Mol]

Hi Anthony,

I am using a Norsat 9000LD Ka band LNB with a homemade horn antenna, and a Nooelec NeSDR XTR receiver. The setup is described in more detail in the first few posts. There is also an article about this project in the July- August SARA journal. 

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[Eduard Mol]

Hi Dimitry,

The double line is unlikely to be the result of Zeeman splitting. I found a paper discussing the details of the Zeeman effect in 22.2GHz water masers (https://adsabs.harvard.edu/pdf/1992ApJ...384..185N). I did not read it in detail, but as far as I could understand it seems like Zeeman splitting is often much smaller than the line width, and is often detected as a (very) small degree of circular polarization. 

The two peaks in my Cepheus A spectrum are a few km/s apart, I think they represent two clumps of gas (maser spots) moving at slightly different line-of-sight velocities. 

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[Anthony]

Thank you, Eduard!

Amazing work!

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[Dimitry UA3AVR]

OK, Eduard, thanks. By the paper, Zeeman splitting is about tenths of km/s.

понедельник, 17 октября 2022 г. в 10:16:04 UTC+3, eddiem...@gmail.com:

[Jim Abshier]

Does anyone know if the July-August SARA Journal has been published.  I
have not received a notification with the link to it.

Jim Abshier

On 10/17/22 2:27 AM, Eduard Mol wrote:
> Hi Anthony,
>
> I am using a Norsat 9000LD Ka band LNB with a homemade horn antenna,
> and a Nooelec NeSDR XTR receiver. The setup is described in more
> detail in the first few posts. There is also an article about this
> project in the July- August SARA journal.
>
>
> On Sun, 16 Oct 2022 at 22:12, Anthony <itpart...@gmail.com
> <mailto:itpart...@gmail.com>> wrote:
>
> Hi Eduard,
>
> Congratulations! I may have asked this before and pardon me if I
> have, what type of LNA, BPF, are you using?
>
>
> On Sun, Oct 16, 2022 at 3:34 PM Eduard Mol <eddiem...@gmail.com
> <mailto:eddiem...@gmail.com>> wrote:
>
> Hi all,
> Last week the water maser in the star forming region Cepheus A
> was successfully observed. The first successful observation
> was done on the evening of October 9. Two weak peaks were
> detected very close to the expected LSR velocity of -10 km/s.
> The integration time was approximately 60 minutes. The
> observation was repeated on October 10; this time the peaks
> were a bit stronger and the SNR was better as well. This could
> be due to better observing conditions or more accurate pointing.

> CepA_091022b.png

> 41e47ba9-26ab-4d34-a7cf-b23b7ba13435.png
> Cepheus A is the sixth water maser source observed with the 1-
> metre "mini maser telescope", the other sources are W49, W51,
> W3, Orion KL and W75N. It seems that there are more than a few
> sources detectable at 22.2 GHz with relatively modest equipment.
>
>
>
>
> On Sun, 9 Oct 2022 at 14:53, Dimitry UA3AVR
> <ua3avr...@gmail.com <mailto:ua3avr...@gmail.com>> wrote:
>
> Well done, Eduard, congrats! I did note the W3(OH) object
> emits the H20 radiation too. Hope to see these line in future.
>
> воскресенье, 9 октября 2022 г. в 13:00:16 UTC+3,

> eddiem...@gmail.com <mailto:eddiem...@gmail.com>:

>
> Hi all,
>
> Last night I observed the W3 region again. There are
> two water maser sources in this region; W3(OH) and
> W3(2). W3(OH) is usually the strongest of the two.
> MaserDB lists LSR velocities of -48 to -50 km/s for
> the main peak of W3(OH) and -35 to -41 km/s for W3(2).
> Last winter I already did some observations of W3, but
> since I had no frequency reference it was not possible
> to calculate LSR velocities and figure out whether the
> detected lines belonged to W3(OH) or W3(2).
> I just processed the data from last night's
> observation session, and to my surprise there is no
> signal at the expected velocity of W3(OH). Instead,
> there are three peaks at -37, -39 and -41 km/s, which
> is more consistent with W3(2). Alternatively, the
> frequency correction or LSR correction could be off.
> However, W51m was observed as well yesterday as part
> of my W49/ W51 monthly observation program, and the
> peak velocity of 58 km/s is consistent with my earlier
> observations and with the LSR velocities listed in
> maserDB. So a mistake in the frequency or velocity
> correction seems less likely. I will try to repeat my
> observations later this month to see what is going on
> here...

>>>> W49driftscanplot1.pngW49driftresult1.png

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[Anthony]

Same here...

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[Dr. Rich Russel]

All

The July-August Journal was published in August. The link was sent to everyone who was a member at that time. 

The next journal link for Sept-Oct 2022 journal will be sent out this week and will give access to members for all of the latest journals too.

Rich

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[Anthony]

Thanks, Dr. Rich,

Searching....

[Jim Abshier]

As far as I know, I am supposed to be a member. I paid my dues back in
June 2022.

Jim Abshier


On 10/17/22 3:21 PM, 'Dr. Rich Russel' via Society of Amateur Radio

> > <mailto:itpart...@gmail.com <mailto:itpart...@gmail.com>>>

> wrote:
> >
> >     Hi Eduard,
> >
> >     Congratulations! I may have asked this before and pardon me if I
> >     have, what type of LNA, BPF, are you using?
> >
> >
> >     On Sun, Oct 16, 2022 at 3:34 PM Eduard Mol
> <eddiem...@gmail.com <mailto:eddiem...@gmail.com>

> >     <mailto:eddiem...@gmail.com

> <mailto:ua3avr...@gmail.com <mailto:ua3avr...@gmail.com>>>

> wrote:
> >
> >             Well done, Eduard, congrats! I did note the W3(OH)
> object
> >             emits the H20 radiation too. Hope to see these line
> in future.
> >
> >             воскресенье, 9 октября 2022 г. в 13:00:16 UTC+3,
> > eddiem...@gmail.com <mailto:eddiem...@gmail.com>

> <mailto:eddiem...@gmail.com <mailto:eddiem...@gmail.com>>:

> >                 <ua3avr..@gmail.com

> <mailto:ua3avr...@gmail.com>> wrote:
> >
> >                     OK, Eduard, thanks ...
> >                     ... a rough estimate is what of needed to know
> >                     detection chances (and keeping in mind the
> >                     variability). The maser DB is already accessible
> >                     again.
> >
> >                     воскресенье, 4 сентября 2022 г. в 23:15:47
> UTC+3,

> > eddiem...@gmail.com <mailto:eddiem...@gmail.com>:

> >
> >                         Hi Dimitry,
> >
> >                         For some reason I could not access maserDB
> >                         today, maybe it is temporarily offline,
> but if
> >                         I remember correctly the flux densities
> >                         reported there were in the order of
> thousands
> >                         to tens of thousands Jansky.
> >                         Actually determining the flux density
> from my
> >                         own measurements is difficult, because I
> have
> >                         no calibration source and variations in the
> >                         amount of water vapor in the atmosphere have
> >                         to be accounted for. I did make a rough
> >                         guesstimate of the flux of W49 from my own
> >                         measurements, which was around 26000 Jy, so
> >                         quite strong indeed.
> >
> >                         Op za 3 sep. 2022 om 21:14 schreef Dimitry
> >                         UA3AVR <ua3avr...@gmail.com

> <mailto:ua3avr...@gmail.com>>

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[Eduard Mol]

Hi all,

It has been a while since I posted about this project, but that does not mean I have been doing nothing all this time. I am still doing monthly observations of W49 and W51, but I will report on those observations later on.

In the meantime I have been trying to detect other masers as well. Attempts to detect G97.312+3.282 and NGC7129 were unsuccessful. I have also tried to detect W44: five observations of this region have been done so far.

The large positive and negative spike in the spectra from the 27-10 and 18-1 is an artifact; it is in fact the zero IF spike of the SDR which is sometimes not completely removed after bandpass correction. A very weak signal was consistently detected at 56.5 km/s. This signal is more obvious after averaging the results from all five observation sessions, although the SNR is still only 5.6. 

 According to the data published on MaserDB the peak emission of W44 is usually at 60 km/s, so the peak I detected seems a few km/s off for W44. The peak at 56.5 km/s seems more consistent with the nearby star forming region G34.403+0.232, which is located just 10 arcmin north of W44.

 This is the seventh water maser source to be successfully observed with the 1 metre dish. Hopefully there will be more successful observations in 2023 :)

Eduard

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[Job Geheniau]

Nice results Ed!

Keep the work ongoing.

The last nice thing I remember when I was at your house was your nice remark:" well we have a nice and strange hobby/interest which only a few people like to practise nowadays..." 

'amateur' Radio Astronomy RULEZ : -). HAHHAHA

But still again, nice results from your Maser hunt, my friend.

Ave Job

Op woensdag 18 januari 2023 om 21:10:42 UTC+1 schreef eddiem...@gmail.com:

[Eduard Mol]

Hi all,

Again a little update on the water maser project.

Over the past few months I have observed W49 a couple times. The region at around -5 to -15 km/s seems to be particularly active, with maser features emerging and disappearing in a few months. The flaring feature at -5 km/s, which emerged in August 2022, became the strongest peak in the spectrum last winter, but has now subsided somewhat. The fact that these maser features are so variable on short timescales suggests that the gas clouds emitting these maser lines are relatively small and presumably close to the host protostar.

W51 has decreased in brightness by over two orders of magnitude, although I still have no method to convert the vertical scale of my spectra to Jansky so it is hard to tell by how much the flux density actually decreased. Since this maser is no longer easily detectable I decided to pause monthly observations of this source in favour of other masers. 

Other masers (re)observed in the past few months are W3(OH)/W3IRS5, W75, Orion KL and NML Cygni.

 

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[Anthony]

Hi Eduard,

This may be a dumb question, but are you able to detect G97.312+3.282 and NGC7129, at 666.6 GHz, instead of the 22.2 GHz?

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[Eduard Mol]

Hi Anthony,

That’s not a dumb question at all, unfortunately I do not have equipment for 6668 MHz. I have tried to detect the sources you mentioned at 22.2 GHz, but so far without success.

Best, 

Eduard

Op vr 2 jun. 2023 om 16:37 schreef Anthony <itpart...@gmail.com>

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[Dimitry UA3AVR]

Eduard, nice work and spectrum evolution pictures ... thanks, it's interesting to look at.

четверг, 1 июня 2023 г. в 21:35:21 UTC+3, Eduard Mol:

[Eduard Mol]

Hi all,

After a few months pause I have started doing observations again at 22.2 GHz. Yesterday the 1 metre dish was pointed at the star forming region G25+694+1.050, also known as IRAS 18316-0602. This region hosts one of three known "kilomasers" in our galaxy, these are maser sources which exhibit very intense flaring in the 10^5- 10^6 Jy range (see also https://ui.adsabs.harvard.edu/abs/2019ARep...63...49V/abstract). Most of the time, however, IRAS 18316-0602 has a flux density of a few hundred Jy and sometimes as low as 10 Jy, so this is a challenging object for small dishes. One has to be lucky to catch it when it is flaring. 

IRAS 18316-0602 appears to be quiet at the moment. Last year August this source was not detected. In March a weak signal was detected at 40 km/s, but I was not able to do a follow-up observation until yesterday. Integration times of both observing sessions are about 1.5 hours. I was pleased to see a peak at the same LSR velocity several months later. This is now the ninth water maser source detected with the 1 metre dish.

[djl]

good stuff!

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------------
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Roseanne Rosannadanna
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[Dimitry Fedorov]

It's nice and good luck ... congradulations, Eduard!

пн, 31 июл. 2023 г., 04:23 djl <d...@montana.com>:

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[Anthony]

WOW, congratulations, Eduard!

I hope one day to develop such skills, once I get my system corrected and stable. 

Please keep sharing! 

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