Observation Log - April 6, 2000

Observation Log - April 6, 2000 - Tinton Falls, NJ

NGC6058, a planetary nebula in Hercules, magnitude 13, diameter 0'.4 (24"). This is a composite image created from 21 exposures totaling 21 minutes, all taken between 3:12 a.m. and 3:37 a.m. the morning of the 6th. Images were taken using the f/6.3 focal reducer, for an effective f/ratio of f/4. Images were processed with dark frame removal, flat frame, then compositing, Digital Development (FFT low-pass, mild), and a contrast stretch. Here is another version of this image, enlarged two times, to show the structure of the planetary in a little more detail.

M13, a globular cluster in Hercules, also known as the "Great Hercules Cluster", magnitude 5.8, diameter 21', distance 23,400 light years. This is a composite image created from 6 exposures totaling 12 minutes, all taken between 3:57 a.m. and 4:20 a.m. the morning of the 6th. Images were taken using the f/6.3 focal reducer, for an effective f/ratio of f/4. Images were processed with dark frame removal, flat frame, then compositing, Digital Development (FFT low-pass, mild), and a contrast stretch. This cluster has between 300,000 and 500,000 stars in a ball with a diameter of about 140 light years.

M86, an elliptical galaxy in Virgo, magnitude 8.9, dimensions 8'.9 x 5'.8, distance 55 million light years. This is a composite image created from 12 exposures totaling 34 minutes, all taken between 2:04 a.m. and 02:42 a.m. the morning of the 6th. Images were taken using the f/6.3 focal reducer, for an effective f/ratio of f/4. Images were processed with dark frame removal, flat frame, then compositing, flatten background, and a contrast stretch. At the bottom right corner is another galaxy, NGC 4387, a 12th magnitude galaxy, 1'.9 in diameter. It appears that there is another faint galaxy to the left and above M86 (approximately the 10:30 position).

M59, an elliptical galaxy in Virgo, magnitude 9.6, dimensions 5'.4 x 3'.7, distance 55 million light years. This is a composite image created from 10 exposures totaling 31 minutes, all taken between 12:40 a.m. and 01:34 a.m. the morning of the 6th. Images were taken using the f/6.3 focal reducer, for an effective f/ratio of f/4. Images were processed with dark frame removal, flat frame, then compositing and a contrast stretch. In his book "The Messier Objects," author Stephen James O'Meara mentions that he was "surprised to see a sharp star-like nucleus, because you hardly ever see one in a long-exposure photograph." In order to see this feature in my image, I used the MaxIm Digital Development filter (FFT low-pass, mild) to bring out the core detail in this image. While processing this image, I also noticed what looked liked another galaxy toward the top of the frame. With an extreme contrast stretch, you can actually see what look like three little galaxies in a rough line toward the top and left of the frame. I have yet to identify these galaxies, but will post ASAP.

[From David Segelstein, 04/10/00: Gordon, I can't identify the little faint one at the upper right, but the one nearer the middle top, above and left of the bright star, is IC 3672, a 14.5 magnitude elliptical galaxy, size 0.9 by 0.8 minutes. The elongated one on the left is VCC 1921, a 15.9 magnitude lenticular galaxy, size 1.1 by 0.4 minutes. Nice catches! ] [From Mark Jaworsky, 04/11/00: Now for the interesting part: The Revised Index Catalogue designates it (the unidentified object) as an elliptical galaxy, magnitude 16.0, 0.5 x 0.4 arcminutes in size. However, if it is a galaxy it should appear in the NED. A search of that database for IC 3670 reveals "no object found" meaning it is not(?) extragalactic. Going to 'The Sky', it designates IC 3670 as an open cluster which would explain why it is missing in the NED. However, it does not really look like an open cluster. If it is anything other than a galaxy, I would say a globular but nothing at that position is listed in W.E. Harris' "CATALOG OF PARAMETERS FOR MILKY WAY GLOBULAR CLUSTERS". Finally the NGC/IC database lists its type as: "Unknown / Unverified". Therefore it is a big ? What would you say it is? ][Mark added later: It's definitely a galaxy. I would guess either an Sc or an SBc. Well, I didn't find any listings or classifications of IC 3670 so I took matters into my own hands. First I found blue light and red light images of it on the POSS II survey. I saved these as GIF files on my hard drive and imported it in my photo editor. I increased the gamma parameter and lo and behold two beautiful spiral arms and perhaps even a bar began to emerge, especially in the blue light image! ]

M60/NGC4647, two galaxies in Virgo. M60 is on the left, an elliptical galaxy, magnitude 8.8, dimensions 7'.4 x 6'.0, distance 55 million light years. NGC 4647 is on the right, magnitude 11.4, length 2'.5. The centers of these two galaxies are separated by 2'.5. This is a composite image created from 11 exposures totaling 34 minutes, all taken between 11:38 p.m. and 12:31 a.m. Images were taken using the f/6.3 focal reducer, for an effective f/ratio of f/4. Images were processed with dark frame removal, flat frame, then compositing, MaxIm Digital Development (FFT low-pass, mild hardness), and finally a contrast stretch.

NGC4438/4435, two galaxies in Virgo. NGC 4438 is on the left, magnitude 10.1, length 9'.1. NGC 4435 is on the right, magnitude 10.9, length 3'.0. From 10:24 p.m. to 11:29 p.m. I took 16 more images of these galaxies (which were first images 3/31 below) for an additional 39 minutes of integration time. These images were composited with the original images, to produce a final composite with a total exposure of 87 minutes. Here are three versions of the image, one at low contrast, to show detail in the cores, one at medium contrast to show detail in the outlying portions of the galaxies, and one at high contrast to show what I believe are a two more very faint galaxies in the field. Look for one in the bottom right corner, and one at about the 8 o'clock position relative to NGC 4438.