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In this session, I had planned to apply the
3.3 focal reducer mentioned in previous reports. In order to mount it, I had
to disassemble the DSI, uncoiling the ocular piece and holding a T-adapter
in its place. In the cavity below, there is a rectangular IR filter glued
on a circular transparent support, which must be removed carefully. The disassemble
task was fine, and everything seemed going perfectly. However, when the T
adapter was being tightened, the IR filter was suddenly broken. The filter
is indeed very poorly designed: If the cavity had been just circular and so
the filter, no problems would have happened. Anyway, removing the filter seems
to have introduced no detrimental effect: the image quality was very good
without it, even better than with it I dare to say. What happened at F/D 3.3?
Well, the field size was very comfortable: 20´15 arcmin instead of 10.5´8 at F/D:6.3, so the location of faint objects
was very simple; the limiting magnitude was also fine. However, I got awful
stellar images. A bright star showed for instance an image similar to strong
comma, but lacking of radial symmetry with regard to the optical axis. Something
similar happened with faint stars once the shot was image processed. I took
a couple of shots (M1 and M42), and owing to the poor results, I decided to
go back to F/D:6.3. Next week I will contact the Meade dealer to consult the
problem. I also used a Hartmann mask. This is a very simple device: just a
circular cardboard covering the corrector plate with two holes symmetrically
arranged. When the image is not well focused, the telescope shows for each
star two light spots that tend to merge as the focus is enhanced. When the
focus is the best, only one spot remains. It is very simple but very accurate.
Finally, I have not solved yet the problem with the RS232C adapter, so the
stacking process did not implied mechanical compensations. The night has been
transparent although light polluted, especially to the south (the doom of
light of Valencia), but at least 5.5 magnitude stars were perceptible to the
zenith. I am very pleased this time with the 16 final images got, shown below.
This has been the first true deep sky
session. Now I am feeling comfortable enough to look for really faint objects.
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7 25.6 +29 29 GEM
PLNNB:3a+6/13m/74''X54'' Stacking 14
images of 15 seconds each. It is striking the green colour of the main lobes
(N2371 north and N2372 south). The outer shell is also weakly visible at the
E and W sides.
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9 55.9 +69 41 UMA GALXY:S/9.2m/10.5'X5.1'65ºAP Stacking 20
images of 15 seconds each. This is one of my best images taken so far. I
never had thought to be able reveal so subtle and intricate structures in the
core region (note the differences in colour, too).
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11 11.5 +55 40 UMA
SB/10.6m/8.6'X2.4'80ºAP Stacking 10
images of 30 seconds each. This galaxy, one of the hardest Messier objects in
small telescopes, shows remarkable dark lanes and a bright foreground star at
the W of the core.
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NGC 2419, The Intergalactic Tramp 7 38.1 +38 53 LYN
GLOCL:2/10.4m/6.2' Stacking 21
images of 15 seconds each, maximum entropy treatment. This is one of the most
remote globular clusters, just mottled with 17.5" telescopes, but well
resolved in this image; stars are of 18 m ( ???).
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11 14.8 +55 01 UMA
PLNNB:3a/11m/202''X196'' Stacking 12
images of 30 seconds each. Highly evolved planetary nebulae with two
symmetrical dark areas. One of the most relevant features is the stratification
in colour, green inside (oxygen), red outside (hydrogen).
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9 32.2 +21 30 LEO SBbc/9m/12'X5.6'/17ºAP Stacking 15
images of 30 seconds each. Magnificent spiral structure, one of the nicest recorded
until now. Prominent bar and semi stellar core, with ramified spiral arms,
more prominent to the W.
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9 32.2 +21 30 LEO
SBbc/9m/12'X5.6'/17ºAP Stacking 18 images
of 20 seconds each. This is one of my favourites galaxies, an immense spiral
strongly mottled and complex at the telescope with a small satellite NGC 4627
to the north (below in the picture).
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Abell 1656, the Coma
Berenices Galaxy Cluster 12 59.8 +27 59 COM
GALCL:2/11m/157' Stacking 17
images of 20 seconds each. This was a great surprise. I could register around
two dozens of galaxies. The main elliptical to the right is NGC 4874. A lot
of 16 and fainter galaxies are visible in the picture.
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12 36.0 +27 58 COM
SB/10.3m/11.0'X4.9'150ºAP Stacking 4
images of 20 seconds each. The spiral arms are particularly wide and intense.
Some IC nebulae, such as IC 3564 or IC 3551, can be seen, even in a short
exposure like this one.
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9 47.3 +67 55 UMA
S/10.8m/6.2'X3.1'143ºAP Stacking 8
images of 30 seconds each. Bright, but with not a prominent core. The surface
is irregularly mottled, crossed by patches apparently without any order. In
the picture almost seems an irregular galaxy.
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M 42 core and trapezium (NGC 1976) 5 35.3 -05 23 ORI
CL+NB:E+R/4m/90'X60' Stacking 5
images of 10 seconds each. The core of M42, showing the Trapezium and the
glowing gas surrounding it. Compare this image with the equivalent in the 22‑Jan‑2005 session,
specially in star resolution.
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J 900 (de Jonkeere 900, PK194+2.1) 6 26.0 +17 47 GEM
PLNNB:3b(2)/12.4m/12''X10'' Stacking 15 images
of 20 seconds each. This planetary nebulae was the first faint I tried when I
built my old 12 cm Newtonian. It is semi stellar object, slightly elliptical,
with a characteristic green colour that allow to catch it.
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The Black Eye Galaxy, M 64 (NGC 4826) 12 56.7 +21 41 COM
S/9.3m/10.3'X5.0'115ºAP Stacking 4
images of 30 seconds each. I repeated the image taken in the first session
and this time the outer spiral structure was recorder (see 22‑Jan‑2005 picture)
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13 12.9 +18 10 COM
GLOCL:5/7.7m/14.4' Stacking 20
images of 10 seconds each. Again, compare this image with the 22‑Jan‑2005 picture.
This time, the processing needs were far more simple.
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12 36.3 +25 59 COM S/10.3m/14.9'X2.0'136ºAP' Stacking 10
images of 30 seconds each, to replace the image taken 22‑Jan‑2005 session. This time the fainter
blue spiral arms are well registered.
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9 55.6 +69 04 UMA
Sb/6.9m/24.9'X11.5'/157ºAP Stacking 28
images of 15 seconds each. I had to have recorded it with a longer
exposition. The spiral structure is only guessed in these conditions.
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