by Albert Highe
There was enough uncertainty in the weather forecasts for the weekend that I canceled my plans to drive to Plettstone on Friday. The CSC and local forecasts were consistently predicting partly cloudy, foggy, damp conditions. However, the satellite images weren't in total agreement. Although the Central Valley was completely blanketed in fog, higher elevations were clear (Michelle reported the skies had cleared Friday night). I trusted the satellite images the most. However, the main question was what the humidity was going to be at Plettstone.
On Saturday, the CSC and local forecasts continued to predict some clouds and fog. In contrast, the satellite images showed drier air moving northeast towards Plettstone. I reasoned that fog in the Central Valley was the result of wet soil from recent rains coupled with radiative cooling into clear skies. If dry air was moving into the area, it may do little to remove fog from the Central Valley, but it could keep Plettstone dry. Despite the uncertainty, I decided to risk the drive.
The skies were clear when I left the Bay Area. However, once I crested Altamont Pass past Livermore, the Sun disappeared. I drove through the fog and low clouds (the stuff seen on satellite images) for the next couple of hours. However, once I got above about 1500' driving into the Sierra foothills, the skies were perfectly clear. Looking back, the Central Valley was filled with fog as far as I could see.
So, how did the night turn out? It was among the best nights I've ever had at Plettstone. The temperature never got below the mid-40's. Because the wind was dead calm, it seemed much warmer. I was warm enough that I didn't have to wear a hat. The relative humidity never got above 73%. Dew was never an issue. Transparency was excellent. M33 was naked eye. I had little difficulty observing detail in faint galaxies and bagging even dimmer faint fuzzies.
As a bonus, the skies were the darkest I've ever experienced at Plettstone. That is saying a lot because Plettstone is already a dark site. The fog in the Central Valley blocked the major sources of light. Light domes from closer sources were also absent because of the low humidity. It was so dark it was difficult to see the ground, even hours after being dark-adapted.
Winter observing has some advantages. The sun sets early and the nights are long. Despite the excellent conditions, fatigue forced me to stop at 1PM - after seven hours of observing! Hardier individuals could have observed until dawn. Cold and damp weather are the major drawbacks to winter observing. Both were absent, making this a particularly enjoyable night.
It would have been worth the drive for just the one long excellent night. However, I decided to stay another night. The satellite images indicated a band of clouds would pass through during the day, but the skies should clear by nightfall. That is exactly what happened. By noon, the sky was completely covered with clouds. By nightfall, the last of the band of clouds could be seen disappearing over the southeast horizon. Temperatures were about 5°F cooler than Saturday night. There was a hint of breeze early, and it felt noticeably cooler than the previous night. By 9PM, the wind was again dead calm. Relative humidity climbed to 80%, but dew never formed. Transparency was excellent and seeing was a little better than on Saturday. Again, it was DARK.
| Scope | 12-1/2" f/5 Mark IV with ServoCat GOTO and Argo Navis |
|---|---|
| Eyepieces | 7mm and 9mm Nagler T6, 14mm and 18mm Radians, and 24mm Panoptic |
I observed over a hundred objects during the two nights. About 80% were new observations, mostly of NGC objects. The remaining observations were of eye-candy and objects I'd observed before.
(all observations made with 7mm Nagler T6 unless otherwise noted)
NGC 77 (mag 14.8, 0.4' X 0.4') Notable only because it was one of the more difficult objects I observed. Could hold this very small galaxy with averted vision 30% of the time.NGC 142 (13.8, 1.1' X 0.6') NGC 143 (14.4, 1.0' X 0.3') NGC 144 (13.8, 0.8' X 0.8') Close triplet of galaxies forming a right triangle. From NGC142, which lies at the W corner, NGC143 is 4' NNE and NGC144 is 3' ESE. Despite having different magnitudes, they appear to have similar size and brightness. Apparent brightness agrees with reported surface brightness (13.0 - 13.2). After extended study, I could hold each with averted vision.
NGC 232 (13.3, 0.9' X 0.7') NGC 235 (13.2, 1.3' X 0.7') NGC 235A (13.0, 0.4' X 0.4') Close triplet. NGC235 is oval and is the brightest member. Has very bright core. Can see brighter core with direct vision. Oval halo more obvious with averted vision. NGC232 is 2' SW and appears elongated. Could hold it steadily with averted vision. NGC235A is very close small companion to NGC235 - 20" SE. Could split it from NGC235 and hold it 60% of the time with averted vision.
NGC 7805 (13.3, 1.0' X 0.7') NGC 7806 (13.5, 1.2' X 0.9') Closely spaced matching pair of galaxies oriented SW-NE. Separation = 1'. Fairly "bright", i.e. can see with direct vision.
NGC 7817 (11.8, 3.5' X 0.9') This galaxy was a very pleasant surprise. It is bright enough to be easily visible with direct vision. Highly elongated and cigar shaped. Central bright section appears mottled. It reminds me of a smaller version of M82.
NGC 7753 (12.0, 3.3' X 2.1') NGC 7752 (14.3, 0.9' X 0.5') NGC7753 appears to be a nearly face on spiral galaxy. Moderately large with bright central condensation. Easily visible with direct vision. Halo is fairly bright. I detect hints of two spiral arms with averted vision. NGC7752 is a small oval companion 2' SW. I can hold it with averted vision.
NGC 160 (12.7, 2.3' X 1.2') NGC 162 (15.6, 0.9' X 0.2') I mention this pair because of NGC162. The NGC/IC Project page shows a labeled image of the NGC160/NGC162 pair. Uranometria lists it as a galaxy. Steve Gottlieb's list doesn't include a description, which usually means the ID is incorrect. I can hold with averted vision the small blip labeled as NGC162. Most of the time it looks stellar. Sometimes it appears fuzzy, but that could be seeing related. It is much easier to see than one would guess by its total magnitude. Its published average surface brightness is the same as NGC160. I can see the bright core of NGC160 with direct vision, and can hold an elongated halo with averted vision.
NGC 169 (13.2, 2.6' X 0.6') IC 1559 (14.0, 0.6' X 0.2') Very close pair near mag 6 star 3.7' ENE. Despite proximity to the bright star, I can hold each with averted vision. NGC169 is brighter and elongated, oriented E-W. IC1559 is smaller, fainter, slightly oval, and aligned approximately N-S. It is 25" S of NGC169, and almost aligned with its core.
NGC 733? - 2MASX J01562472+3303524 (15.2, 0.6' X 0.3') NGC 736 (12.2, 1.5' X 1.5') NGC 738 (14.9, 0.5' X 0.3') NGC 740 (14.0, 1.6' X 0.4') CGCG 503-53 There seems to be some confusion over the identity of NGC733. NED identifies the object at this location by the 2MASX designation. Uranometria and the image on the NGC/IC webpage designate it as NGC733. Steve Gottlieb doesn't list an observation, so again, I question the assignment. It is very faint. Using a DSS image, I was able to locate its position and eventually hold it with averted vision 30% of the time. NGC736 is the dominant galaxy in this group, being a direct vision target 3.5' ESE. Also in the area is NGC740, a highly elongated galaxy that I could only hold 80% of the time. A 10th mag star 1' E makes viewing difficult. NGC738 is 1.3' NE of NGC736. I could hold this very small oval galaxy 90% of the time with averted vision. I also was able to hold nearby CGCG 503-53 with averted vision 35% of the time.
NGC 750 (11.9, 1.7' X 1.3') NGC 751 (12.7, 1.2' X 1.2') Although I've seen this pair of galaxies before, I had to mention them. They are a beautiful close bright pair, one just slightly larger and brighter, and aligned approximately N-S. They are 14' NE of NGC736. Requires moderately high magnification to clearly see two distinct barely intersecting ovals, only 25" apart.
NGC 7825 NGC 7827 (13.9, 1.2' X 0.9') UGC 33 (14.0, 0.9' X 0.6') UGC 37 (13.7, 1.1' X 0.5') Steve Gottlieb notes that NGC7825 is misidentified in a few lists, assigning it the location of UGC37. Uranometria makes the same mistake. UGC37 is 2.8' S of NGC7827. It has low surface brightness, but I could eventually hold it with averted vision 80% of the time. The true NGC7825 is 5.3' WSW of NGC7827. I could hold this small galaxy with averted vision. NGC7827 is the brightest in this group. I could see the brighter central area with direct vision. A larger circular glow is apparent with averted vision. I could hold UGC33, 5' SSW of NGC7825, 95% of the time with averted vision.
NGC 7821 (13.1, 1.4' X 0.5') 2MASX J00051603-1629348 NGC7821 is visible with direct vision and shows a distinct elongated oval with averted vision. I only note it because of its small companion 1' S. I could hold the 2MASX galaxy with averted vision 30% of the time. Galaxies with 2MASX as the primary designation were only discovered recently by automated surveys or have other less well-known designations. A surprising number are easily observed with amateur telescopes. Although I've observed about 250 such galaxies with the 17-1/2", it is clear that some are visible in even a 12-1/2" scope.
NGC 7828 (13.9, 0.9' X 0.5') NGC 7829 (13.9, 1.1' X 0.7') Something peculiar is happening with these galaxies. I can hold NGC7828 with averted vision. However, 50% of the time, I can resolve it into two components - it appears as an elongated dumbbell. NGC7829 lies along the same line, 30" away from the closest component. It appears stellar with direct vision, but swells into a small fuzzy ball 50% of the time.
Abell Galaxy Cluster 76 IC 1565 (13.4, 1.0' X 1.0') IC 1566 (13.7, 0.8' X 0.7') IC 1568 (13.9, 0.8' X 0.8') While hunting down NGC190 in Uranometria, I noticed this small galaxy cluster 20' SE. I was able to identify three of its members that lie equally spaced along an arc 10' long, running SW-NE. IC1565 was the brightest. I could hold it with averted vision and make out a brighter core. IC1566 was somewhat fainter, but still visible steadily with averted vision. IC1568 was the faintest. I could hold it with averted vision 90% of the time.
NGC 311 (13.0, 1.5' X 0.6') NGC 315 (11.2, 3.2' X 2.5') NGC 318 (14.4, 0.6' X 0.4') Nice trio of galaxies equally-spaced along a line 11' long running SW-NE. Big, bright NGC315 is in the center, easily visible with direct vision. It is slightly oval and has a bright core. A 9th mag star lies 3.5' SE. At the SW end of the line is NGC311. It is much smaller and fainter, but still just visible with direct vision. With averted vision, it appears oval. NGC318 is at the other end of the line. It is easy to overlook with the brighter pair close by. I was able to hold this very small oval with averted vision.
NGC 524 Galaxy Group NGC 532 (12.9, 3.1' X 1.0') NGC 518 (13.3, 1.7' X 0.6') NGC 509 (13.4, 1.6' X 0.6') NGC 505 (13.8, 1.0' X 0.7') NGC 502 (12.8, 1.1' X 1.0') NGC 489 (12.7, 1.7' X 0.4') NGC 524 (10.3, 2.8' X 2.8') NGC 516 (13.1, 1.4' X 0.5') NGC 525 (13.2, 1.5' X 0.6') NGC 522 (12.9, 2.7' X 0.4') IC 101 (13.8, 1.4' X 0.6') Members of this galaxy group appear stacked in a loose pyramid configuration with north at the top. All objects are new observations except for NGC524, the largest and brightest member of the group. All are rather easy to see (detect with direct vision or hold with averted vision) except for IC101. I could hold it with averted vision only 30% of the time. NGC532 deserves special mention. It was noticeably elongated and looked irregular. The brighter central area appeared wedge-shaped.
NGC 660 (11.2, 8.3' X 3.2') Bright, moderate size, elongated, irregular galaxy. Bright core with some mottling. Halo appears asymmetric, fanning out toward SW.
NGC 812 (11.3, 2.2' X 0.8') Bright and considerably elongated. Appears irregular.
Circle of six galaxies NGC 996 (13.0, 1.2' X 1.2') NGC 995 (13.4, 1.3' X 0.6') NGC 1000 (14.6, 0.7' X 0.7') NGC 1005 (13.8, 1.0' X 0.8') NGC 1001 (14.8, 0.9' X 0.5') NGC 999 (13.5, 1.2' X 0.8') These six galaxies lie around the perimeter of a circle with a diameter of approximately 14'. NGC996 is the largest and brightest of the group, but all are rather easy to see (detect with direct vision or hold with averted vision). The list indicates each galaxy's position in clockwise order around the circle.
Geminids Meteor counts were higher than normal during both nights. The radiant appeared to be in Gemini. On Saturday, around 10PM, I counted 5-6 bright streaks within two minutes.
Horsehead Nebula With the 24mm Panoptic and H-beta filter, one of the best views I've seen. Contrast between the "bright" nebulosity and the dark notch was high.
M46 One of my favorite open clusters. I always look forward to viewing it each winter. It fit nicely within the field of the 24mm Panoptic. At low magnifications, the superimposed planetary nebula, NGC2438, is visible as a small ethereal disk. At higher magnification the disk resolved into a thick, mottled ring.
Saturn Open up your planetarium software and view the arrangement of Saturn's moons on December 12, 2004, around 11:30PM PST. Dione, Tethys, Rhea, and Titan form a striking pattern. The moons followed a smooth arc curving northward along the eastern edge of the rings. The progression was even more impressive since the moons appeared in order of brightness.
Since I sold my 17-1/2" and started using the new 12-1/2" scope, I've concentrated on observing NGC objects that I haven't seen before. I expected most objects to be challenging since I've already observed over 2000 NGC objects (including having completed Herschel I and II lists and observed most objects plotted in Sky Atlas 2000). I've been very surprised to find so many galaxies that are rather "easy" to see. Some almost qualify as "eye-candy". They reveal substantial detail. It calls into question the criteria used to create existing lists. I continue to discover interesting targets that are brighter than many objects I've already observed. It sure pays to venture off the beaten track.
Always a pleasure to visit Michelle and observe at Plettstone.
Posted on sf-bay-tac Dec 15, 2004 14:58:30 PT
Converted by report.pm 1.2 Feb 06, 2005 22:59:36 PT