Dr Anthony Cook from BAA/ALPO TLP Coordinator reports that he "will add the Galdies observation to the LTP catalog with a weight of 1, just to encourage observers to try to replicate the effects seen. At least the color was not too dissimilar to that seen by Paul Abel and others back in 2009, and also lay in terrace shadings, but in the case of the Abel observation, was more confined to the NW".
Data analysis and comments:
The Lunar Observer, September 2012
 |
| Color images of Eratosthenes by Charles Galdies. Philips SPC 900NC PC camera (color space/compression YUY2) on a Nexstar 8SE telescope. Air temperature 27.5C, dew point 21.8C, wind 9.3 km/h SSW, 15 km visibility i.e. a clear sky. Each image is a result of running Registax 6.0 using 3000 frames, with 95% best frames and wavelet transform. Further processed for reproduction in the newsletter, with a contrast stretch and slight increase in color saturation. North is towards the top left. (Far Left) UT19:44:11-19:45:01. (Centre Left) UT 19:47:28-19:48:18. (Centre Right) UT19:48:19-19:49:08. (Far Right) 19:50:33-19:51:23. |
1. OBJECTIVE: Verification of the
following historical LTP:
2012-Aug-25 UT 19:30-19:50 Ill=64%
Eratosthenes observed by Abel_P on 2009-11-25
On 2009 Nov 25 UT18:42-21:03 P.Abel,
T.Little and C.North (Selsey, UK,
15" reflector, seeing II-III,
transparency very good), all saw visually a brownish tinge on the north west
rim of Eratosthenes crater. P.Abel
made a sketch and T.Little took some
high resolution CCD images, some
of which were through coloured filters.
Checks were made for spurious
colour, but none was seen elsewhere on
the Moon. The eyepiece was
changed but this made no difference.
M.C.Cook (Mundesley) was observing
with a smaller scope at the same time,
but saw no colour, however
observing conditions were worse.
W.Leatherbarrow (Sheffield, UK) was
observing with a instrumenet mid way in
size, and saw a brownish tinge
in the NW rim area, but saw a similar
colour elsewhere and put this
down to spurious colour. Normally
multiple observers seeing the same
thing would result in a weight of 4,
however as this was only observers
at Selsey and some of the evidence
contradicts, I am allocating an
ALPO/BAA weight=3.
 |
| Sketch of Eratosthenes showing brown on the NW rim. Drawn by Paul Abel from 2009 Nov 25 UT 18:42?-20:18. North is towards the top left. |
2. METHOD
Equipment & Software
Used:
Nexstar 8SE
NEQ-6 Pro mount
Philips SPC 900NC PC Camera
SharpCap, Registax 6.0
LTVT: advanced software tool for lunar topography.
LTVT: advanced software tool for lunar topography.
Atmospheric conditions @
1800UT:
Ambient air temperature: 27.5degC
Dew point:
21.8degC
Wind: 9.3
km/h SSW
15km
visibility
Clear sky
Comments on CCD settings,
data capture and processing:
The
Gain setting of the camera was adjusted to emphasise the illuminance and colour
of the inner western walls of
Eratosthenes. Background detail was not deemed as important and is therefore seen
in a rather low illuminance. For normal, routine imaging of the lunar surface,
higher Gain values are normally used to keep a balanced level throughout.
No
colour filters were used, and camera settings were kept consistently the same
throughout the observation session.
[Philips SPC 900NC PC Camera]
Resolution=640x480
Frame Rate (fps)=60.00
Colour Space / Compression=YUY2
Exposure=-4
Brightness=64
Contrast=32
Saturation=0
Gamma=15
ColorEnable=255
BacklightCompensation=0
Gain=45
The
total number of images sometimes exceeded 6000 per CCD session. However, because
of Registax restrictions, image stacking was done for batches of up to 3000
images taken at 60 fps.
No
post-processing of the final stacked image was performed, other than wavelet
transform using Registax.
3. RESULTS
LTVT simulation (for physical data) at start and end of the recording period: 19:44:11 UT & 19:52:14 UT
LTVT simulation (for physical data) at start and end of the recording period: 19:44:11 UT & 19:52:14 UT
Data analysis and comments:
UTC
From:
|
UTC
To:
|
Appearance and/or comments(if brightness being measured, enter value in last column) |
19:44:11
|
19:45:01
|
Rather low
illuminated western inner walls, with a very slight hint of colour change
|
19:47:28
|
19:48:18
|
A hint of
a reddish-brown hue is evident in shadowy areas of the western inner walls of
the crater. No other area within the image exhibited this change. Most
prominent colour change occurred at: Long: 12:04 o W; Lat: 14:78 o N with a
sun altitude of 2.16o degrees and azimuth 92.14 o degrees (data taken from
LTVT)
|
19:48:19
|
19:49:08
|
Prominent
brownish colour still evident but with some slight overall diffusion. Most
prominent area however remained located at: Long: 12:04 o W; Lat: 14:78 o N with
a sun altitude of 2.17o degrees and azimuth 92.14 o degrees (data taken from
LTVT).
|
19:50:33
|
19:51:23
|
A slight
change towards a brownish, diffuse colour was detected. The diffusive effect
seemed to have diminished, but this may be due to transient atmospheric
conditions. Turbulent conditions probably increased due to decreasing
altitude of the moon (altitude=32017” @ 19:48UT).
|
19:51:24
|
19:52:14
|
Brownish,
diffuse shadowed colour still evident but of conspicuously less intensity
than at 19:48 UT
|
19:52:15
|
-
|
Observation
terminated as previous timing of this LTP report expired
|
LTVT Predictions of the same phenomenon:
Colongitude = 14.682 with Solar Lat = -1.519
Librations
and Moon/Sun positions calculated for observer at 14.260°E 35.520°N
85 m
Terminators Sub-Solar Point Librations Center of Moon Center of Sun
Date
Time UT Morning Evening
Colong Lat. Long.
Lat. Alt. Azi.
Alt. Azi
25/08/2012 19:48:45
14.682°W 165.318°E 14.682 -1.519
1.483 -1.308 26.600
208.829 -24.841 305.091
+%
24/09/2012 07:47:05
14.682°W 165.318°E 14.682 -1.283
4.993 -4.970 -63.708
54.156 33.285 119.059
+
16/07/2013 17:58:45
14.682°W 165.318°E 14.682 -1.429
-6.686 2.112 39.791
191.834 2.710 294.320
+
15/08/2013 05:05:24
14.682°W 165.318°E 14.682 -1.495
-4.823 -2.052 -72.715
340.013 7.665 78.245
+
13/09/2013 16:46:10
14.682°W 165.318°E 14.682 -1.155
-1.422 -4.638 32.522
162.243 4.612 271.066
+
06/06/2014 16:29:15
14.682°W 165.318°E 14.682 -1.161
-4.779 3.958 49.652
151.343 19.260 284.629
+
06/07/2014 03:27:29
14.682°W 165.318°E 14.682 -1.507
-7.245 0.950 -52.505
307.748 -5.378 57.088
+
04/08/2014 14:26:55
14.682°W 165.318°E 14.682 -1.457
-7.058 -2.459 24.001
133.378 42.591 260.557
+
03/09/2014 01:51:41
14.682°W 165.318°E 14.682 -1.019
-7.509 -5.237 -40.965
275.334 -31.304 51.329
+
27/05/2015 01:52:08
14.682°W 165.318°E 14.682 -1.318
-0.114 2.816 -20.412
287.954 -20.150 42.653
+
25/06/2015 12:56:50
14.682°W 165.318°E 14.682 -1.555
-1.911 -0.902 9.878
104.547 63.034 250.872
+
24/07/2015 23:52:54
14.682°W 165.318°E 14.682 -1.389
-5.930 -3.349 -12.174
263.059 -33.769 12.309
+
15/05/2016 11:12:30
14.682°W 165.318°E 14.682 -1.431
6.196 0.701 -13.593
73.564 73.249 190.880
+
13/06/2016 22:26:18
14.682°W 165.318°E 14.682 -1.554
2.562 -1.953 19.547
251.323 -30.571 350.151
+%
13/07/2016 09:21:49
14.682°W 165.318°E 14.682 -1.274
0.819 -5.052 -37.660
73.958 62.918 113.379
+
05/04/2017 08:12:51
14.682°W 165.318°E 14.682 -1.079
5.932 3.603 -33.992
27.638 40.731 116.093
+
04/05/2017 20:26:14
14.682°W 165.318°E 14.682 -1.492
6.507 -0.141 54.538
228.989 -26.793 318.113
+%
03/06/2017 07:53:00
14.682°W 165.318°E 14.682 -1.500
6.965 -3.560 -49.645
30.689 47.225 94.802
+
02/07/2017 18:51:49
14.682°W 165.318°E 14.682 -1.112
5.391 -5.502 45.835
191.191 -5.961 303.825
+%
+ = Latitude of sub-solar point within 0.50°
of target (= -1.519°)
% = Moon above horizon/Sun below horizon