Observing Report: Whitaker's M5?
Jim Mosher
the Moon's south pole the last few evenings, or have noticed any
photos of it posted on the internet?
Since the Moon passed north of the Sun at conjunction, the illuminated
crescent passed over the south pole; and, although far outside the
LCROSS "mission parameters", the lighting and librations remain
favorable for seeing polar dots wrapping over and beyond the Moon's
south pole, as shown in the first attachment. The white lines on the
lunar globe represent the Moon's equator and prime meridian (line of
zero longitude), while the red and blue lines delimit the illuminated
terminator or the right. I was away on the evenings of Feb 26 and 27
(UT = Wed & Thurs evenings in California), but was home to look at the
poles on Friday evening (Feb 28) from ~2:30 to 4:00 UT.
The dots come from high points, lit basically from the rear. For
elevated points, a small bit of the sunlit slopes may be visible from
Earth. The sequence and intensity with which they appear should, one
would think, be useful in validating high resolution models of the
polar topography. As Derek has pointed out, it's unfortunate the
Moon, when seen in a thin crescent phase, is so low in the Earth's
sky. Otherwise it might well be an ideal geometry for observing an
impact from Earth (depending on how the amount of light scattered by
dust varies with angle), especially if the impact were targeted at a
shadowed peak, just short of catching the Sun's rays (unfortunately,
not a likely spot for ice).
The second attachment is a crude sketch of how the southern cusp
looked on Friday evening, drawn from memory on Saturday morning, then
scanned, inverted and rotated to approximate the conventional mapping
orientation. Boussingault, completely filled with shadow, was an
easily recognized landmark and its identity could be confirmed by the
presence of Helmholtz and Neumayer nearby, as shown. Poleward from
Boussingault was a somewhat chaotic region followed by two distinct
scallops produced by Demonax and Scott, with bright "dots" at the
cusps/tips of the scallops. Beyond the scallops, a continuous, but
very thin, ribbon of light extended to a final (and much dimmer) dot.
Nothing but could be seen beyond that dot, except possibly Earthshine.
I was wondering if this final dot might possibly be the farside,
western hemisphere peak Ewen Whitaker calls M5?
http://the-moon.wikispaces.com/Whitaker%2C+1954
A quick eyeball estimate suggested its distance beyond the poleward
cusp of the final (Scott) scallop slightly exceeded the width of the
two scallops (Scott + Demonax) together. This placed the dot well
beyond where the pole would be expected to lie, but close to the
azimuth where M5 might be.
The appearance I observed was vaguely similar to that shown in the
third attachment, a photo by Henrik Bondo:
http://ltvt.wikispaces.com/file/detail/MTe43_20maj_2041UT_Dob2PM_4303px_qu6.jpg
which also shows a (faint) final dot at what appears to be the same
location; although the interior of Boussingault was completely dark
when I looked (no detail visible inside it), the scallops at Scott and
Demonax were more distinct, and there was a continuous thin ribbon of
light connecting the final dot to the Scott scallop.
The coordinates of M5, read from the latest Kaguya topographic map,
are: 118.36W/ 85.38S. Based on this, the viewing conditions were, and
will be, as follows:
Date/Time Sun Alt Sun Az Center Dist.
--------- ------- ------ ------------
Henrik -2.99 251.2 88.5
Feb 26 +0.12 280.7 87.5
Feb 27 -0.87 268.5 86.4
Feb 28 -1.87 256.4 85.7
Mar 01 -2.81 244.2 85.3
where the first line gives the circumstances of the photo (Sun's angle
and azimuth as seen from M5 and distance of M5 from disk center, all
in degrees), and the last four are for recent evenings (UT dates) from
my location at 03:00 UT.
The interaction of sun angle with azimuth for polar peaks is not at
all obvious, especially in the case of one, like M5, on the "wrong"
side of the pole. The sun angle was highest on Feb 26, but since the
lighting is from the rear, very little of it is visible from Earth.
By March 1, the Sun should have swung around to where the sunlit
slopes are more visible from Earth, but the lighting angle is then so
low they will mostly be in darkness.
The idea that M5 could be in sunlight with a sun angle well below
zero, as in Henrik's photo, is not completely unreasonable since it is
a tall peak, and at these azimuths it is being lit by sunlit streaming
over the much lower South Pole-Aitken basin. But if the identification
of the final polar dot with M5 is correct, this dot should probably
have been even more evident on the evenings I missed, and it should
probably be fading out tonight.
-- Jim
Derek C Breit
I haven't opened this yet (but I have every other issue - No Worries..) but
I believe the following message means there is an article about LCROSS...
Derek
www.poyntsource.com/New/index.htm
Dears Friends, I like to share with you "SELENOLOGY TODAY",
available online the issue #13
Selenology Today 13
http://digilander.libero.it/glrgroup/
There is a special issue of LCROSS and also images taken by GLR
about south pole region comparing them with the consolidated lunar
atlas (modern CCD images with old images taken in the past e.g CLA)
Selenology Today is an online journal devoted to the study of the
Moon. It is a free, welcoming contributions from professional and
serious amateur .
Also preceding issue are present in the website.
Raffaello Lena
GLR group
Derek C Breit
I can't ID anything, but yes, there was most definitely a LONG ribbon of
light connecting to this point of light.. It was certainly as far from the
nominal cusp as I have ever seen..
Derek
Derek C Breit
and do that Sunday..
Derek
Jim Mosher
designated "M5(?)" in the previous post (Feb 28 UT):
http://groups.google.com/group/lcross_observation/msg/74e99923a04aad5e
continued to be visible last night (2009 Mar 01 03:00-04:00 UT).
This time I tried taking a crude photo, handheld through an eyepiece
with not quite enough eye relief for the purpose. The result is shown
in the first attachment, taken at 03:38:42 UT.
With a fatter crescent, the cusp looked wider and less scalloped than
on the previous night, but despite the general increase in brightness,
the thin line I recall connecting the final dot to the lighted part
seemed to have dissolved into darkness. There was a definite gap.
Also Amundsen was becoming more obvious between Scott and the limb --
the final scallop seen the previous night was really a combination of
the two.
As previously noted, the distance from the poleward rim of Scott to
the mystery dot is slightly more than the combined diameters of Scott
and Demonax. That places it well to the west of the pole, whose
approximate position is indicated by the blue tick mark (SP). If the
final dot is Whitaker's M5, the sun angle would have been -2.8 deg at
the time of this photo.
The second attachment shows the same photo compared to an earlier
photo by Clif Ashcraft, remapped to the same geometry. As indicated
by the arrows at corresponding locations, Clif's photo shows an
extremely faint dot at what looks like it might be the leading edge of
the same feature. The sun angle at the center of M5 would have been
-3.4 deg at the time of Clif's photo. For comparison of features,
there is a fiducial "+" mark near the centers of the two images, most
evident in Clif's image, where it is just to the right of a bright
patch, which is the "northern" flank of the large plateau Whitaker
calls Leibnitz Beta (where it abuts Scott). Scott M, on the plateau,
is just to the right of the "+" mark, and a little farther to the
right is Malapert E (see Whitaker's map for orientation).
The Leibnitz Beta bright patch is prominent in my photo as well, and
was one of the two bright points at the cusps of the scallops noted
the previous night (Feb 28 UT), the other being the high ground
between Scott and Demonax (to the left in the second attachment).
Just below the Leibnitz Beta bright patch, Clif's photo shows a thin,
diagonal bright streak. This streak was very evident visually last
night (next to the Leibnitz Beta bright patch), although my photo
barely captures it. Also visible to the right of the Leibnitz Beta
bright patch were two isolated bright dots, which show up very fuzzily
in my photo. These can be identified with corresponding high points
in Clif's photo.
Finally, Clif's photo shows the beginnings of a dot which will grow
(as the Sun swings around in colongitude) into the peak designated by
Whitaker as Malapert Alpha. The sun angle at its peak would have been
at an altitude of about +1.1 deg from an azimuth of 85 deg at the time
of Clif's photo.
I thought I saw something at the limit of vision near this point last
night, but it could have been slightly farther to the right. At the
time I was looking, the sun angle at the summit of Malapert Alpha
(2.63E/85.99S) would have been -3.0 deg from an azimuth of 123 deg.
For a feature of this sort, the azimuth, as well as the altitude, of
the Sun is critical because the surrounding terrain is different in
every direction. Although a sun angle of -3.0 deg seems low compared
to the +1.1 deg in Clif's photo, Lunar Orbiter photo IV-044H shows
some light on the peak at about the same sun angle and azimuth, so
perhaps something *was* visible.
-- Jim
P.S.: By tonight (2009 Mar 2 02:00 UT -- Sunday evening on the US west
coast) the sun angle at the summit of M5 (118.36W/85.38S) will be -3.6
deg, very slightly lower than at the time of Clif's photo. The
following night it will be -4.4 deg. If the identification is correct
it should continue to dim even though it is well onto the disk and the
terminator might look like it is moving towards it (since the
terminator revolves about the pole, it moves in one direction on the
earthward side, and in the opposite direction on the farside, where M5
is located).
Jim Mosher
early parts of the lunation was left dangling because I missed the
opportunity to look for it on the evening of Mar 1 (local)/Mar 2 (UT),
and, as best as I can recall, was unable to see it the following night
(if I looked).
Since, then Richard Wilds has kindly sent me several scans of drawings
of south polar lighting by famed British amateur Harold Hill:
http://the-moon.wikispaces.com/Hill%2C+1991
including the attached one from March 27, 1985, when M5 (at a location
of 118.36W/85.38S) was lit from behind at a sun angle of -2.3 deg.
Obviously, the idea that M5 might be responsible for the most distant
dots seen in the cusps of young crescent Moons is no original to me!
The sky is quite clear here today, so I should have a chance to see if
any trace of M5 is visible this evening. M5 will be well onto the
visible hemisphere, and the sun angle will be higher than at the time
of Hill's observation, but more from the rear. I could not see it
last night (Mar 27 local/ Mar 28 UT), but the Moon was pretty low and
the seeing was imperfect.
M5 is unusual in that (because it is in the "wrong" hemisphere), in
the first stages of the lunation the sun angle is decreasing, so that
it disappears, only to reappear when the Sun swings around to the
front. It should disappear earlier this lunation than last because
the Sun is rapidly moving north of the Moon's equator, producing
longer shadows and lesser illumination at the southern pole (both
librations and lighting had a strong southerly bias at the time of
Hill's drawing).
-- Jim
Jim Mosher
M5 (or what I take to be M5) was readily visible last night (2009 Mar
29 UT at ~03:00 UT) as a dot beyond the southern cusp of the young
crescent.
The view was much like that shown in the drawing from last month. A
thin ribbon of light extended beyond the twin scallops of Demonax and
Scott, with a bright dot (M5) appearing, after a short gap, at the
end. The sky was quite clear (for here) and the gap appeared to be
about the same brightness as the general Earthshine (which was dimly
visible over the "dark" portion of the lunar disk). The sunward-facing
side of Leibnitz Beta was also visible.
It's cloudy here today, so I don't know if I'll have a chance to
observe it again tonight; but those who might be interested, here is
an LTVT printout detailing the lighting for the next few days for M5
(118.3600 W / 85.3800 S) as seen shortly after sunset from my location
at 117.8941 W 33.6439 N (the UT date is one day after the local
calendar date).
The sun is currently swinging around to the Moon's Earthward side, so
most features are becoming more visible, but at the same time it is
moving away from M5 giving a lower and lower sun angle there. It will
probably no longer be visible as a polar dot on the night of March
31st (April 1 UT), when the sun angle falls below -4.5 deg. It should
start becoming sunlit again in the second week of April, but will, by
then, be so far beyond the limb that at most its peak will be visible.
---------------------
Lighting table for M5
---------------------
Center Sun Angle
Date Time UT Distance Altitude Azimuth
3/27/2009 03:00:00 85.9906 0.0826 287.557
3/28/2009 03:00:00 85.5190 -0.8903 275.382 <-- couldn't see
(?)
3/29/2009 03:00:00 85.4352 -1.8831 263.206 <-- readily
visible
3/30/2009 03:00:00 85.7614 -2.8519 251.025
3/31/2009 03:00:00 86.4898 -3.7535 238.834
4/1/2009 03:00:00 87.5811 -4.5481 226.629
4/2/2009 03:00:00 88.9690 -5.2003 214.410
...
4/9/2009 03:00:00 98.8649 -4.4102 128.860
4/10/2009 03:00:00 99.2772 -3.6009 116.698
4/11/2009 03:00:00 99.3221 -2.6961 104.553
4/12/2009 03:00:00 99.0200 -1.7367 92.419
4/13/2009 03:00:00 98.4068 -0.7657 80.288
4/14/2009 03:00:00 97.5280 0.1729 68.153
--
By comparison, here are the results for Malapert Alpha (2.6300 E /
85.9900 S). Since Malapert Alpha is on the Earthward side and in the
eastern hemisphere (where the Sun is coming from), the sun angle there
increases steadily in the early part of the lunation. Malapert Alpha
does not become visible at as low a sun angle as M5 because the
sunlight has to pass over higher terrain to reach it (M5 can be lit
from the rear at very low sun angles because the terrain in that
direction is very low). I was not able to see anything at its
expected position last night (2009 Mar 29 UT), and do not expect to
see it for several more nights.
---------------------------------
Lighting table for Malapert Alpha
---------------------------------
Center Sun Angle
Date Time UT Distance Altitude Azimuth
3/27/2009 03:00:00 80.2682 -5.2091 166.467
3/28/2009 03:00:00 79.7540 -4.9325 154.208
3/29/2009 03:00:00 79.6057 -4.4926 141.962 <-- not
visible
3/30/2009 03:00:00 79.8529 -3.9106 129.734
3/31/2009 03:00:00 80.4946 -3.2138 117.526
4/1/2009 03:00:00 81.4978 -2.4348 105.337
4/2/2009 03:00:00 82.8004 -1.6098 93.165
4/3/2009 03:00:00 84.3173 -0.7765 81.006
4/4/2009 03:00:00 85.9485 0.0271 68.853
4/5/2009 03:00:00 87.5872 0.7648 56.702
4/6/2009 03:00:00 89.1279 1.4032 44.549
4/7/2009 03:00:00 90.4755 1.9137 32.392
4/8/2009 03:00:00 91.5528 2.2733 20.228
4/9/2009 03:00:00 92.3070 2.4657 8.061
4/10/2009 03:00:00 92.7122 2.4820 355.890
4/11/2009 03:00:00 92.7688 2.3212 343.720
4/12/2009 03:00:00 92.4986 1.9900 331.553
4/13/2009 03:00:00 91.9381 1.5029 319.391
4/14/2009 03:00:00 91.1321 0.8811 307.233
-- Jim
Jim Mosher
solidly overcast skies, M5 was easily visible again last night
(Monday, Mar 30, 2009 Pacific Time), but I had some trouble
photographing it. It could be seen as a relatively bright star-like
dot, separated from the remainder of the southern cusp by a broad,
dark gap. Its identity could be easily confirmed since its distance
along the limb from the bright Leibnitz Beta promontory (see attached
photos) was (as expected) just about equal to the combined widths of
Scott and Demonax or the other side.
In the photos, the last major bright splotch preceding the end of the
cusp is the north-facing slope of Leibnitz Beta (where it abuts and
extends the south inner wall of Scott). Visually, a distinctive
bright angled linear dash (like an "acute" accent in the French
alphabet) could be seen above it (the features are blurred together in
the photo). The dash is high ground poleward from Scott E and (at
this phase) helps to confirm one is looking at Leibnitz Beta.
Because of problems with vignetting of the handheld photos, the
photometry is not very reliable; but M5 certainly appears to have
become dimmer relative to Leibnitz Beta, and since it was so hard to
capture, it was probably dimmer on an absolute scale as well (M5 is
marginally visible in the second photo if one adjusts the gamma
sufficiently).
On an absolute scale, the remainder of the illuminated crescent
appears to have brightened substantially, with most of it in the
second photo being as bright or brighter than the brightest parts in
the first photo.
I am not sure if M5 will remain visible tonight, since (according to
the table in the preceding posting) the sun angle will have become
quite low. In any event, it seems unlikely I will be able to capture
it with the camera.
In the Moon's northern cusp, several isolated dots were visible last
night, but they were dimmer than M5 (or at least looked that way to my
eye), and not as far separated from the remainder of the cusp. I have
not yet attempted to analyze which peaks they were.
-- Jim
P.S.: there are nice recent full disk mosaics showing the Moon's north
and south poles linked to from today's LPOD:
http://lpod.wikispaces.com/March+31%2C+2009
and from this internet posting:
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/3015414/page/0/view/collapsed/sb/5/o/all/fpart/1
Both show nicely the "acute" accent over Leibnitz Beta that I was
trying to describe above, but neither is exposed deeply enough to show
the bright dot of M5. As indicated above, the distance from Leibnitz
Beta to the M5 dot is just about equal to the combined widths of Scott
and Demonax.
Jim Mosher
small faint features on the Moon, I previously mentioned that I was
unable to see the polar dot on the recent LPOD photo and the mosaic
posted by Pete Lawrence. I misspoke. It is true I couldn't seen them
on the LCD monitor at the public library, but when I brought them home
and looked at those photos on my older CRT display, the dot was quite
apparent (at least in a darkened room). The first attachment shows
these, and a new mosaic posted by Pete:
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/3017439/page/0/view/collapsed/sb/5/o/all/fpart/1#Post3018038
adjusted to the same scale and orientation, and unmercifully increased
in brightness and gamma. All three show the dot (or dots) at the same
position.
The second attachment is a reference image from LPOD showing what the
region (and M5) looks like when the lighting is from the front. It
has *not* been corrected for the difference in longitudinal libration,
which skews features a bit, form left to right.
The LCROSS impact will presumably create a plume consisting of sunlit
dust particles, probably with a reflectance not all that different
from M5. They may present to the viewer somewhat more favorable
angles than the slopes of M5; but at the same time it seems likely
they will fill only a tiny fraction of the projected area. As a
result, they may well be as hard or harder to see than this "solid"
polar dot.
M5 was *not* visible to me last night (2009 April 1 ~03:30 UT).
-- Jim
Derek C Breit
As a result, they may well be as hard or harder to see than this "solid"
polar dot.
-------------
Precisely why imaging the darklimb is needed..
:-))
Derek