New Images uploaded to files section
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Arnold Ashcraft
Feb 16, 2009, 8:21:13 AM2/16/09
to LCROSS_Observation
Folks:
I have uploaded two new images to the files section. The first is
of the north lunar limb and was made from a video taken at 4:17 am EST
under poor to fair seeing conditions. There was a broken thin cloud
cover with some haze at the time the video was taken. The other image
is a single frame of a video taken of the 7.68 magnitude star TYC 6766 291
as it passed the south limb of the moon. Exposure time was 53.5 ms, 7.5 fps.
The exact time the frame was taken was 09:54:56.639 UT
File Name CAshcraft_20090216_091956_UT
Name of observer: Clif Ashcraft
Email address of observer: wa2...@optonline.net
Aperture of telescope: 184 mm
Focal length of telescope: 2578 mm
Type of camera used: The Imaging Source DMK31
Camera detector dimensions: 1024x768 pixels (uncropped)
Exposure information: 23.9 ms at 30 fps, 897 frames taken.
Time and date of exposure: 2009-02-16 09:19:56 UT
Red #25 and NIR blocking filters used with baffled nosepiece.
Location from which exposure was taken: Perrineville, NJ
File Name CAshcraft_20090216_095457_UT
Name of observer: Clif Ashcraft
Email address of observer: wa2...@optonline.net
Aperture of telescope: 184 mm
Focal length of telescope: 2578 mm
Type of camera used: The Imaging Source DMK31
Camera detector dimensions: 1024x768 pixels (uncropped)
Exposure information: 53.5 ms at 7.5 fps. Only frame 49 used
Time and date of exposure: 2009-02-16 09:54:56.639 UT
Red #25 and NIR blocking filters used with baffled nosepiece.
Location from which exposure was taken: Perrineville, NJ
Clif
Jim Mosher
Feb 16, 2009, 5:20:18 PM2/16/09
to lcross_ob...@googlegroups.com
Nice work, as usual, despite the poor seeing, Clif!
I'm attaching enlargements from your two most recent north polar
photos highlighting (with the white arrows) the location of Hermite A,
the crater containing LCROSS target site "B". The section shown
extends from Hermite, the large flat-bottomed crater in the upper
left, to Gioja, the prominent shadowed one in the lower right. What
looks like a small black-white crater just above the arrows is related
to the newly-named Aepinus, but the crater itself is between this and
Hermite A (see explanation of third attachment below).
The elliptical outline of the near and far rims of Hermite A's bowl is
clearest in the Feb 14th photo, where what is presumably the far rim
(or more precisely its sunlit far inner wall) can be seen as a thin
ribbon of light with an only slightly wider ribbon of darkness below
it (corresponding to the shadowed crater interior). As seen from the
center of Hermite A, the Sun was at an elevation of 2.51 deg above the
horizontal and at an azimuth of 182.5 deg (measured clockwise from a
meridian towards the north pole, that is, from almost due south).
In the Feb 16th photo, which was taken with the Sun at an elevation of
2.34 deg and an azimuth of 207.4 deg, the far rim is less clearly
defined, but the area of sunlit inner wall near the tip of the
right-hand arrow appears to have brightened and enlarged relative to
comparable features nearby. Since the Sun is slightly lower, yet
there is more light on the wall, this suggests that the opposite rim
(over which the Sun is shining) must be lower at this azimuth than at
the other one, even though the crater as a whole appears to be tilted
up a bit on the left side. This behavior seems consistent with the
latest Kaguya topographic map shown (as pointed out by Derek) in the
Feb. 13th issue of /Science/ (see the third attachment), where the rim
of Hermite A appears to have a partial opening on the side towards
Hermite. The Sun may be shining through that low spot. Or it may just
be a difference in the seeing and exposure/processing.
Your south polar photo gives a nice view of the peak(s) between Short
and Newton. Short is the shadowed crater immediately behind Moretus,
and Newton is to its upper right, just inside the limb, with its left
half hidden by the tall, bright peak. For reasons unknown to me,
people rarely photograph the limbs when the features there are tipped
away from Earth; but as you photo shows, at least parts of the
topography can be much clearer then than in the traditional photos.
It's quite difficult, for example, to deduce the importance of this
peak when it is seen projected onto the disk.
-- Jim
P.S.: I assume you will not be offended if I observe that, useful as
these may be, these are probably not the best-ever amateur photos of
the Moon's north pole. The second attachment shows a detail from an
LPOD photo taken with a similar strong libration but under better
conditions by Damian Peach:
http://www.lpod.org/?m=20070103
It is shown with twice as many pixels per kilometer as the first
attachment. I am guessing Damian took it shortly before sunrise, at
around 09:00 UT, at which time the sun angle at the center of Hermite
A would have been 2.5 deg at an azimuth of 201 deg -- rather similar
to your second photo, but with quite a different libration in
longitude. The location of Hermite A is again shown with arrows, but
the inner wall on the right, that you show in bright sunlight, is
unfortunately outside the frame.
The Moon's less photogenic north pole appears to attract relatively
little attention, so its surprisingly hard to locate good photos of
it. But the higher resolution of Damian's view is a great help in
correlating the features seen in your photo with those shown in
satellite views. For example, the bright-dark pattern that I took to
be Aepinus in your photos is actually not exactly that: above and
midway between the arrows in the first attachment is a floating blob
of light. Damian's photo shows this as a bright and crisply-defined
pyramid of light, which is clearly a peak rising above the sunlit far
inner wall of Aepinus -- a feature easily recognizable on the Kaguya
Laser Topo map (see third attachment). Aepinus itself must lie
entirely in front of (and somewhat to the left of) this peak. The
arrows in the second attachment give an accurate indication of its
size, but the shadowed interior is difficult to distinguish on
Damian's photo, and not at all recognizable on yours. The much fatter
area of shadow to the left of, and curving around the suspended blob
of light -- which I took to be the shadowed bowl of Aepinus in your
photo -- is actually a low area beyond the named crater, ringed by a
more distant ridge.
The third and final attachment shows the relevant section of the new
Kaguya Laser Topo map, in an aerial view adjusted to the same scale as
the first attachment, and rotated so that the limbward direction as
seen from New Jersey on Feb. 14th is vertically up. The high point on
the far rim of Aepinus producing the pyramid of light is evident, as
is the more distant ridge that seems to curve around it when viewed
from Earth, and the shadowed low spot in between. Damian's LPOD photo
was taken with the limb in a more clockwise direction, so the distant
ridge does not appear to wrap around the foreground one as much in
his.
Dwelling on Aepinus at such length may seem a bit silly, since it
isn't a LCROSS target, but the crater-looking feature seen near that
point is located close to the point where Hermite A is expected to be
seen in Earth-based photos and could easily be confused with it.
Incidentally, to demonstrate that even experts can misidentify
features near the limb, the LPOD referenced above incorrectly
identifies the features seen beyond Hermite in Damian's photo. The
vast, shadowy walled plain beyond Hermite is Rozhdestvenskiy, and the
bright arc to the left (in the photo) is the sunlit inner wall of
Rozhdestvenskiy K, a large crater superimposed on it. Lovelace (which
it is identified as being) would have been well onto the visible disk
and out of the frame to the left.
I'm attaching enlargements from your two most recent north polar
photos highlighting (with the white arrows) the location of Hermite A,
the crater containing LCROSS target site "B". The section shown
extends from Hermite, the large flat-bottomed crater in the upper
left, to Gioja, the prominent shadowed one in the lower right. What
looks like a small black-white crater just above the arrows is related
to the newly-named Aepinus, but the crater itself is between this and
Hermite A (see explanation of third attachment below).
The elliptical outline of the near and far rims of Hermite A's bowl is
clearest in the Feb 14th photo, where what is presumably the far rim
(or more precisely its sunlit far inner wall) can be seen as a thin
ribbon of light with an only slightly wider ribbon of darkness below
it (corresponding to the shadowed crater interior). As seen from the
center of Hermite A, the Sun was at an elevation of 2.51 deg above the
horizontal and at an azimuth of 182.5 deg (measured clockwise from a
meridian towards the north pole, that is, from almost due south).
In the Feb 16th photo, which was taken with the Sun at an elevation of
2.34 deg and an azimuth of 207.4 deg, the far rim is less clearly
defined, but the area of sunlit inner wall near the tip of the
right-hand arrow appears to have brightened and enlarged relative to
comparable features nearby. Since the Sun is slightly lower, yet
there is more light on the wall, this suggests that the opposite rim
(over which the Sun is shining) must be lower at this azimuth than at
the other one, even though the crater as a whole appears to be tilted
up a bit on the left side. This behavior seems consistent with the
latest Kaguya topographic map shown (as pointed out by Derek) in the
Feb. 13th issue of /Science/ (see the third attachment), where the rim
of Hermite A appears to have a partial opening on the side towards
Hermite. The Sun may be shining through that low spot. Or it may just
be a difference in the seeing and exposure/processing.
Your south polar photo gives a nice view of the peak(s) between Short
and Newton. Short is the shadowed crater immediately behind Moretus,
and Newton is to its upper right, just inside the limb, with its left
half hidden by the tall, bright peak. For reasons unknown to me,
people rarely photograph the limbs when the features there are tipped
away from Earth; but as you photo shows, at least parts of the
topography can be much clearer then than in the traditional photos.
It's quite difficult, for example, to deduce the importance of this
peak when it is seen projected onto the disk.
-- Jim
P.S.: I assume you will not be offended if I observe that, useful as
these may be, these are probably not the best-ever amateur photos of
the Moon's north pole. The second attachment shows a detail from an
LPOD photo taken with a similar strong libration but under better
conditions by Damian Peach:
http://www.lpod.org/?m=20070103
It is shown with twice as many pixels per kilometer as the first
attachment. I am guessing Damian took it shortly before sunrise, at
around 09:00 UT, at which time the sun angle at the center of Hermite
A would have been 2.5 deg at an azimuth of 201 deg -- rather similar
to your second photo, but with quite a different libration in
longitude. The location of Hermite A is again shown with arrows, but
the inner wall on the right, that you show in bright sunlight, is
unfortunately outside the frame.
The Moon's less photogenic north pole appears to attract relatively
little attention, so its surprisingly hard to locate good photos of
it. But the higher resolution of Damian's view is a great help in
correlating the features seen in your photo with those shown in
satellite views. For example, the bright-dark pattern that I took to
be Aepinus in your photos is actually not exactly that: above and
midway between the arrows in the first attachment is a floating blob
of light. Damian's photo shows this as a bright and crisply-defined
pyramid of light, which is clearly a peak rising above the sunlit far
inner wall of Aepinus -- a feature easily recognizable on the Kaguya
Laser Topo map (see third attachment). Aepinus itself must lie
entirely in front of (and somewhat to the left of) this peak. The
arrows in the second attachment give an accurate indication of its
size, but the shadowed interior is difficult to distinguish on
Damian's photo, and not at all recognizable on yours. The much fatter
area of shadow to the left of, and curving around the suspended blob
of light -- which I took to be the shadowed bowl of Aepinus in your
photo -- is actually a low area beyond the named crater, ringed by a
more distant ridge.
The third and final attachment shows the relevant section of the new
Kaguya Laser Topo map, in an aerial view adjusted to the same scale as
the first attachment, and rotated so that the limbward direction as
seen from New Jersey on Feb. 14th is vertically up. The high point on
the far rim of Aepinus producing the pyramid of light is evident, as
is the more distant ridge that seems to curve around it when viewed
from Earth, and the shadowed low spot in between. Damian's LPOD photo
was taken with the limb in a more clockwise direction, so the distant
ridge does not appear to wrap around the foreground one as much in
his.
Dwelling on Aepinus at such length may seem a bit silly, since it
isn't a LCROSS target, but the crater-looking feature seen near that
point is located close to the point where Hermite A is expected to be
seen in Earth-based photos and could easily be confused with it.
Incidentally, to demonstrate that even experts can misidentify
features near the limb, the LPOD referenced above incorrectly
identifies the features seen beyond Hermite in Damian's photo. The
vast, shadowy walled plain beyond Hermite is Rozhdestvenskiy, and the
bright arc to the left (in the photo) is the sunlit inner wall of
Rozhdestvenskiy K, a large crater superimposed on it. Lovelace (which
it is identified as being) would have been well onto the visible disk
and out of the frame to the left.
Arnold Ashcraft
Feb 16, 2009, 6:09:00 PM2/16/09
to lcross_ob...@googlegroups.com
Jim:
No offense taken. I am just happy that anything is recognizable
in my photos given the lousy seeing! Thanks for identifying the LCROSS
target for me. Wish I had the nice laminar flow air you sometimes
get off
the Gulf of Mexico in the islands where Damian vacations instead of the
lumpy stuff that blows my way after making it through the Appalachians.
Clif
> <ClifAshcraft_HermiteA_labeled_by_JMM.jpg><DamianPeach_Hermite_LPOD_la
> beled_by_JMM.JPG><Clif_14Feb2009_area_KaguyaLaserTopo.JPG>
No offense taken. I am just happy that anything is recognizable
in my photos given the lousy seeing! Thanks for identifying the LCROSS
target for me. Wish I had the nice laminar flow air you sometimes
get off
the Gulf of Mexico in the islands where Damian vacations instead of the
lumpy stuff that blows my way after making it through the Appalachians.
Clif
> beled_by_JMM.JPG><Clif_14Feb2009_area_KaguyaLaserTopo.JPG>
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