07/10/21
Location: Anza desert site,
Bortle 3.5
Equipment: Celestron 9.25” Edge HD
SCT and Celestron 150ST
achro on
SW SkyTee 2 manual AltAz mount.
To set the mood here is New Moon and Venus from the other night.
Different weather apps were showing different high clouds patterns. However, since all have promised some clear sky, I took a gamble and went on overnight observing trip to Anza desert. I have arrived to a hot dry weather and clear skies (so far so good
), set the scopes and head leisurely dinner watching sunset colors fade and stars pop up. At 21:21 sky got dark enough to try for some galaxies.
Virgo galaxies (all observed with 9.25” Edge HD
SCT).
NGC 4933A and B – a pair of interacting galaxies. The first thing I have noticed is the round core of
NGC 4933A. After playing with different powers and soaking some photons the faint elongated disk of
NGC 4933A has emerged with averted vision (AV). After more of
EP shaking, moving eye and the field I finally spotted a very faint small disk of
NGC 4933B touching the narrow edge of
NGC 4933B. Pentax XW14 (168X) and XW10 (235x).
NGC 4942 – irregular shape looking like faint fuzzy and patchy crescent. Looking at
NGC 4942 images it appears that the crescent is formed by the core and two brighter spiral arms. Pentax XW14 (168X), XW10 (235x).
NGC 4989 – small narrow disk with compact core, next to Theta Virgo. Pentax XW20 (118X).
Theta Virgo (STF 1724) – attractive triple star – warm white primary with blue secondary next to it and silvery ternary in a distance. Pentax XW20 (118x). Primary itself is a close double with 0.4” separation. I have tried to detect it by airy disk elongation, but the seeing was too poor for that.
In the process I have discovered that my
SCT might be off collimation. I moved the scope to Polaris, dropped in Pentax XW3.5 and defocused. Surely enough the central obstruction shadow was slightly off center. 1/3 turn of 3 o’clock secondary mirror screw took care of that. SCTs hold collimation quit well, but the last few miles to my observing desert site is a rough dirt track, all sorts of screws in all sort of places in my equipment get loose by driving over that.
And back to galaxy hunting
NGC 5210 – faint round disk with AV. Pentax W20 (118x).
Just one hour into the session Virgo was getting low to the Temecula light dome in the west. That was probably the last Virgo galaxy of the season. Until the next year! Booties was still high in the darker portion of the sky, so I switched my attention there.
Booties galaxies (all observed with 9.25” Edge HD
SCT).
NGC 5730 – very faint narrow shape with AV. Pentax XW14 (168X).
NGC 5731 – narrow lens with AV, same
FOV with
NGC 5730. Pentax XW20 (118x) and XW14 (168X).
NGC 5732 – very faint oval with AV. Pentax XW14 (168X).
NGC 5735 – wide faint oval with AV. Pentax XW14 (168X).
HJ 5487 – double star – a pair of faint white tween stars in the same
FOV with
NGC 5735. Pentax XW20 (118x).
NGC 5737 – small faint narrow oval with AV. Pentax XW14 (168X).
NGC 5739 – small relatively bright oval disk with round core off center. Pentax XW14 (168X).
NGC 5747 – faint oval with AV. Pentax XW20 (118X).
NGC 5751 – small faint narrow oval with AV. Pentax XW20 (118X).
NGC 5754 – very faint round disk with AV. Pentax XW20 (118X).
NGC 5760 – very faint patch with AV. Pentax XW14 (168X).
NGC 5902 – small round disk with stellar core. Pentax XW20 (118x) and XW14 (168X).
I would keep going with galaxies but have noticed high clouds creeping from the north. Before they took over, I wanted to test my new Pentax XL 40mm
EP and compared it to other 2” EPs in my case.
My current 2” lineup consists of TV Panoptic 70 deg 27mm (87x, 0.78 deg TFV, 2.7mm exit pupil in 9.25” Edge
SCT), Baader Hyperion Aspheric 72 deg 36mm (65x, 1.1 deg TFV, 3.6mm exit pupil in 9.25” Edge
SCT) and TV Plossl 50 deg 55mm (43x, 1.17 deg TFV, 5.5mm exit pupil). These three EPs supplement nicely my 1.25” 3.5mm to 20mm Pentax XW set. However, I wanted to get another 2” wide field to go with 3mm to 18.2mm TV Delites set. Rather than duplicating what I have I decided to try Pentax XL 65 deg 40mm (59x, 1.1 deg TFV, 4.0mm exit pupil in 9.25” Edge
SCT).
My first target was Ptolemy Cluster (M7). I have chosen it for the large 1.3 deg size. At first glance all four 2” EPs provided nice views in 9.25” Edge. After taken another look TV Plossl 55mm has emerged as a winner due to slightly larger (and very flat) TFV and clean sharp stars.
FOV of Panoptic was too narrow to frame M7 nicely. TFV of Baader Aspheric and Pentax XL were closer to the TV Plossl, however they exhibited astigmatism at the edge of
FOV. They have still provided nice views and I would not necessarily spot the astigmatism if I would not compared them side by side with Panoptic and TV Plossl.
Next target was M4 globular cluster. Here TV Plossl 55mm was at the last place failing to resolve the core due to lower power. Panoptic and Baader Aspheric provided the best views. Pentax XL has shown the same level of features, but somehow they did not pop to view as readily as in Panoptic and Baader Aspheric. It could be that larger exit pupil of Pentax reduced contrast to a small degree. The view it delivered was still very nice and I would not notice small differences if not side by side comparison. Although, while overall structure of M4 was presented somewhat better in Baader Aspheric, Pentax XL has produced cleaner stars.
For the next two targets, Lagoon (M8) and Trifid (M20) Nebulae I have focused comparison on XL40 and Aspheric 36mm since they were competing for the same spot in my
EP lineup. The views in both were gorgeous, the nebulae have shown rich features no filters needed. Upon closer examination Baader Aspheric has delivered a bit better contrast. Most of nebulae features were resolved in both EPs, but with Aspheric they were a bit more vivid. XL40 however delivered cleaner stars again.
Since my main
EP set is used mostly for
DSOs, Baader Aspheric 36mm will remain in it. Pentax XL40 will go to my TV Delites case which I mostly use for double splitting. Cleaner stars produced by XL40 will be advantage there.
Despite some minor differences both Baader Aspheric 36mm and Pentax XL40 are good quality EPs and perform quite nicely in
SCT. However, Baader Aspheric deliver more bang for the buck since it is priced $100 less than XL40 on the used market. I had it for a few years and also like how it performs in my refractors from 80mm to 150mm. That would be my first recommendation for someone looking for a quality low power 2” wide field for a
CAT or frac, but not for a fast reflector.
