May 24, 2009: Plettstone (and response to . 30 year observing project)

Albert Highe

I'm in awe of Steve Gottlieb's observing accomplishments and contributions to amateur astronomy. Observing all of the NGC objects is no small task. I think it is astonishing that he set the goal at a time when the data was flawed and obtaining source material was difficult. I am particularly impressed that he played such a large role in correcting the established databases.

I know my observing logs and astronomy knowledge will never match Steve's. The gap is too great. Those facts don't discourage me. I am inspired by his example and leadership. I am happy to enjoy the benefits of his labors. In particular, I find his meticulous observing logs very useful when I want to compare what I saw or want to know what to expect. They are available through links on the NGC/IC webpage.

Those reading Steve's account shouldn't assume that it now would take a lifetime to observe all the NGC's. Steve's efforts, PC software, and a variety of readily-available hardcopy atlases and on-line databases have removed many of the barriers. For example, I started observing late in life. Currently, I've observed almost 8000 objects. 5800 of those are listed in the NGC. All but 500 were observed during just the past eight years using 6" to 17-1/2" reflectors. Most observations were recorded well before observing all the NGC's became my goal.

If I were a beginning amateur astronomer today, I'd consider observing all the NGC objects soon after I cut my teeth on the Messier list. Alternatively, one could take the intermediate step of observing all the objects in Steve's Deep Map 600 list. A 12-1/2" scope, considered small by some today, would be adequate aperture to observe most of the NGC's.

As Steve pointed out, a fraction of the objects on the NGC list were discovered with apertures as large as 72". Rather than observing all the NGC's, one could consider observing all the NGC's discovered by the Herschel family, or those discovered with apertures below some critical threshold. Typically, the reflectivity of the 18.7" speculum mirror most often used by William and John Herschel provided similar brightness as a modern 16" glass mirror with a standard aluminum coating. In addition, objects can often be observed with smaller apertures if you already know where to look.

With reasonable dedication, planning, and preparation, I think all but a handful of the NGC objects could be observed within 8-10 years using apertures common among deep sky observers. This also assumes that one takes only modest notes. The pace could be maybe 20% quicker if one just checked items off the list. It would take considerably longer if you are as meticulous as Steve.

That being said, I couldn't find a good working list for tackling the NGC objects. I started by downloading the corrected NGC list from the NGC/IC webpage. It contains useful information such as object name(s), coordinates, description, brightness, size, discoverer, year of discovery, aperture used. To make it useful to me, I sorted the objects by constellation and created a separate spreadsheet file for each. The more challenging effort entailed preparing each constellation's list for field use. Using the data on the NGC/IC webpage, and Uranometria, I removed duplicate listings of the same object under different designations, and subdivided the rest into "real objects", "those plotted in Uranometria, but don't exist", "those on the NGC/IC webpage, but not in Uranometria", "objects that exist, but are just single, double, or triple stars". Removing the duplicates and non-existent objects saved frustration and time searching for objects that weren't there. I created finder charts for the few objects that weren't plotted in Uranometria. Since I did not share Steve's interest in observing everything, I decided not to observe stars that were mistaken for other objects and given NGC designations. However, I decided to observe the asterisms.

My working spreadsheets contain object number, coordinates, object type, magnitude, and size. One of the time-consuming tasks was looking up and entering the Uranometria page number where each object can be found. Objects are then sorted by RA within each Uranometria page number. Objects discovered by the Herschel family are highlighted in bold face type to indicate they should be easier to see. A binder contains a printout of all the spreadsheets. I don't need to think much about what I'll observe each month. When I arrive at the site, I work the pages of Uranometria corresponding to the area of sky that looks good and convenient.

While observing, I may spend an hour or two on any given Uranometria page. Spending time on relatively small patches of sky makes star hopping more efficient. One can observe more objects per night. If I can't find something within a couple of minutes, I move on. I make simple sketches of objects relative to nearby stars if the observation is questionable. After I return home, I compare my observations to Steve's descriptions or images on the NGC/IC webpage. For objects I was unable to find, I prefer to download a DSS image directly from the STScI Digitized Sky Survey webpage, create my own finder chart, and place it in the binder behind the appropriate spreadsheet. In crowded galaxy fields, I'll often make a DSS image of the area before I go out. Almost all my DSS images are printed to the same scale. One also could use a laptop in the field. Each approach has pros and cons.

The above approach is effective when one has the luxury of returning to the same fields on successive outings. However, it isn't the most efficient approach. For my observing trips to Australia, I modified the list-creation strategy. Observing lists were created based on individual Uranometria pages. This approach ignores constellation boundaries. When observing an object, there is little reason to ignore others nearby just because they lie on the other side of an imaginary line. Objects are ordered by nearest-neighbor, visually selecting the path that minimizes star-hopping. Although the NGC objects discovered by John Herschel from South Africa are generally brighter, I prepared a large number of DSS images, especially for those crowded in the LMC. If I were starting out today, all my Northern Hemisphere observing lists would be based on this strategy as well.

I enjoy the hunt, and testing my skills, regardless what the object is called. I use the NGC goal as a guideline. While hopping across pages of Uranometria, I often become distracted by objects with other designations: IC, MCG, CGCG, UGC. It is surprising how many of these objects are visible. With greater preparation and using DSS images, many unplotted objects with less common designations are also visible.

Even with the above approaches, I suspect most people will consider observing all the NGC's too daunting. I recommend taking a stab at observing all the NGC objects within one particular constellation. One could start small with Equuleus, containing only a few, or tackle the monster Virgo, containing over 600. There are plenty of constellations that contain 100-200 objects. Observing such a collection will turn up unexpected jewels as well as challenges. Observing all the NGC's within one constellation may embolden a few to tackle the entire list.

Below are selected notes from observing sessions this past Thursday through Saturday at Plettstone. I used a 16" f/4.5 alt-az, undriven reflector, mostly with a 7mm Nagler T6 eyepiece. All object information comes from the NGC/IC webpage.

Conditions were very good to excellent. Temperatures dropped into the high 50's Thursday and Friday, and into the low 50's on Saturday. Humidity was low and winds were negligible all three nights. Transparency was excellent Thursday and Saturday, and excellent on Friday early, and then good over half the sky after Midnight. Seeing was good all three nights.

Corvus was well placed. I completed the final ten objects on my list - on Uranometria pages 130 and 131.

NGC 4726 in Corvus is a good example of identification errors in the NGC and inconsistencies with visual discoveries. The Sky version 5 and Uranometria (new edition) apparently misidentify NGC 4726 as IC 3834. Its location is corrected in The Sky version 6, although this version still lists NGC 4726 at the old location as well.

William Herschel discovered the nearby brighter close pair NGC 4727 (mag 11.9) and 4724 (12.7), in 1785. The discovery of NGC 4726 is credited to Wilhelm Tempel in 1882. I remain skeptical of identifications of visual discoveries. The corrected NGC 4726 is mag 14.8 and lies 5' north of NGC 4727. With the 16", it appears as a very small elongated galaxy that I could hold with averted vision 95% of the time. Yet, apparently a number of brighter IC galaxies within 15' weren't discovered at that time: IC 3822 (12.6), IC 3834 (13.7), IC 3824 (14.6), IC 3831 (13.6), and IC 3827 (13.4). I had little trouble observing them. The brighter cores of some were visible with direct vision. Most appeared brighter than NGC 4726. This is typical of some of the discrepancies the NGC/IC project team has to reconcile. It also illustrates that many lesser known galaxies are relatively easy to see.

NGC 4748 was another interesting object. It has a bright, stellar core visible with direct vision. The halo appears to be slightly oval with averted vision. Upon closer inspection, the halo has a small bump to the NNE that I could hold 85% of the time with averted vision. Occasionally a faint stellar core appeared to wink in and out within it. It turns out this is a separate object with designation 2MASX J12521292-1324388.

I had completed observing all the NGC objects within Cancer last month. But I discovered that NGC 2783 was part of a Hickson Compact Group (#37). I returned to the area armed with a DSS image. I was able to confirm NGC 2783B (IC 2449). It appeared as a highly elongated thin galaxy just visible steadily with averted vision. However, I was unable to see the three MCG members.

With the exception of NGC 3189, I completed the list of NGC objects within Leo last month. I attempted to observe it again each night, but without success. It isn't plotted in Uranometria. The NGC/IC webpage indicates that it was discovered by William Parsons in 1850 with a 72". Steve Gottlieb's observing notes doesn't list it. In the DSS image it appears to be a portion of the bright galaxy NGC 3190 on the SW side of its dust lane. Has anyone seen it?

I had 32 NGC objects remaining on my list for Coma Berenices. I was prepared to complete this constellation as well. It rotated into prime observing position around Midnight.

NGC 5008 lies within Hickson 71. The notes on the NGC/IC site indicate that its NGC identity may be uncertain. It is plotted in Uranometria as IC 4381. It appeared as a circular galaxy with near uniform brightness, just visible steadily with averted vision. In contrast, the nearby IC 4382 showed up nicely on the DSS image I prepared, but was not plotted in Uranometria. It appeared smaller and elongated, but with higher surface brightness. Those were the only two members of HCG71 I could see.

In addition, galaxies NGC 4019, 4042, 4323, and 4752 were not plotted in Uranometria. But with the DSS images I prepared, I was able to observe all of them. Most surprising was NGC 4042 with photographic magnitude listed as 16.4. Its size is a mere 0.1' x 0.1'. Armed with the DSS image, I was eventually able to find and hold it 40% of the time with averted vision. It was discovered by Albert Marth in 1865 using a 48" reflector.

I tired before completing Coma and packed up at 2AM.

On Friday, I started out logging objects in Lynx and then finished the 15 remaining NGC objects on my list within Leo Minor.

In Lynx, NGC 2719 is an example of discovering unexpected interesting objects while slogging through the NGC. NGC 2719 is a small elongated oval with a brighter core that may have been off-center. It has a smaller close companion, NGC 2719A, approximately 0.5' south. It appeared to be more circular, and also contained a brighter core. I could hold each steadily with averted vision.

Within Leo Minor, I enjoyed the rich galaxy field around NGC 3158. This is an example where preparing a labeled DSS image beforehand is helpful. I had observed NGC 3158 before. NGC 3158, and the nearby, but smaller and dimmer NGC 3163, were discovered by William Herschel. There are many other NGC galaxies nearby. To the SSE of NGC 3158, NGC 3163 is one of three (along with NGC 3161 and 3159) nearly collinear galaxies oriented E-W and spanning less than 3'. NGC 3163 is the brightest of the three. It appeared circular with a stellar core that is visible with direct vision. Despite their proximity and brightness, NGC's 3159 and 3161 weren't discovered until later by Guillaume Bigourdan using a 12" refractor. Their halos appeared to be slightly oval, and contained slightly brighter cores. I could hold each steadily with averted vision. I also observed the nearby galaxy MCG+7-21-19. I could hold this small oval with averted vision 75% of the time. West of this grouping are NGC's 3150 and 3151, also discovered by Bigourdan. Their sizes and shapes are similar to NGC 3161, but NGC 3150 was a little dimmer.

Approximately 5' north of NGC 3158 is NGC 3160. 4' west of it is NGC 3152. Both were discovered later by William Parsons with the 72" reflector. Yet, each was readily visible. I was able to hold each steadily with averted vision. NGC 3160 is elongated with a slightly brighter central area. NGC 3152 is a smaller oval with a brighter, small core.

3' east of NGC 3158 is MCG+7-21-25. I saw a fairly "bright" star at this location, presumably the stellar core. I did not detect any halo. I did not detect MCG+7-21-27 located 1.5' further east.

I anticipated completing observations of NGC objects within Coma Berenices. However, around Midnight, crud moved in quickly from the West, reducing transparency over half the sky. I abandoned plans for Coma. Instead, I used my observing lists to jump to first Ursa Major, and then to Cygnus, where the sky was clear. Within Cygnus, I observed two bright stellar planetary nebulas, NGC 6833 and NGC 6884. These planetary nebulas were discovered later, in 1883 and 1884, respectively, using refractors. Since they are stellar, I'm curious how their discoverers determined what they were? Were they discovered using high magnifications in excellent seeing? Of course, today we can identify them using DSS images and know that the star we see is a nebula because someone told us so. In addition, one can "blink" them with an OIII filter, as I did, to confirm their identification.

On Saturday, I nearly completed the NGC objects in Coma. Only one object eluded me: NGC 4529. William Herschel discovered it, so I didn't expect it to be too challenging. Unfortunately, it is long and narrow, making it more difficult to see. I didn't feel so bad when I discovered it is not in Steve's list of observations. I'll prepare a DSS image to assist in its capture next month.

NGC 4019 is plotted as IC 755 in Uranometria. Its identification is listed as uncertain on the NGC/IC webpage. Nevertheless, it appeared as an elongated oval with brighter central area. Brightest portions were just visible with direct vision. Using a prepared DSS image, I was also able to see nearby galaxies CGCG69-20 and MCG+2-31-16. The first appeared as very small, slightly oval galaxy. I could hold it with averted vision 70% of the time. The second appeared to be very small and circular. I could hold it steadily with averted vision.

NGC 4676 was another nice surprise. It is a close pair of galaxies (NGC 4676A and B) known as "the Mice". I had never observed them before. Since they don't have separate NGC designations, I assume William Herschel did not resolve the pair or only saw the brighter of the two small ovals. The NW member is the brighter of the two. I could hold its brighter central area with direct vision. In contrast, the SE member disappeared with direct vision although I could hold it steadily with averted vision. The faint tidal tails that show up in long-exposure photographs were not visible visually.

I spent much of the rest of my time logging galaxies in Lynx and Ursa Major which were well placed. The list for Lynx is now down to a manageable size. Ursa Major will take a while.

In Ursa Major, page 23 of Uranometria shows NGC's 5109 and 5113 as close neighbors. The NGC/IC webpage points out that they are the same object. Only one noticeably elongated galaxy exists near this location. Its brighter central area was visible with direct vision.

Here is the observing tally for the three nights.

1.. Observed 142 new objects (113 NGC's, 14 IC's, 9 MCG's, 5 UCG's, and 1 2MASX) among nine constellations
2.. Reobserved 30 other NGC's along the way
3.. Spent approximately two hours sharing views of Messier objects and looking through others' scopes.

These numbers are typical of my recent NGC-focused observing sessions. I find many fascinating objects most nights, and am motivated to rack up the total. On the other hand, most of my notes contain boring, sketchy descriptions of faint objects.

Paul and Michelle treated us to bar-b-cue both Friday and Saturday nights. Yum. Many thanks to their hospitality. Plettstone continues to be one of my favorite observing venues.

Albert