Observation Log - May 1, 2000 - Coyle Field, NJ

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M8, The Lagoon Nebula, a Diffuse Nebula in Sagittarius, magnitude 4.6, diameter 90' x 40', distance is 5,200 light years. This is a mosaic that shows only part of the core of M8, and it was taken using the f/6.3 focal reducer, giving an effective focal ratio of f/4. This mosaic was made from 16 exposures for a total integration time of 8 minutes. It was processed with dark frame subtraction, flat field, then compositing the top and bottom parts separately, then mosaic assembly, Digital Development (Kernel, low-pass) and finally a contrast stretch. Images were taken between 3:14 a.m. and 3:47 a.m. the morning of the 1st. Here is another version of this image with a considerably higher contrast stretch designed to show more detail in the outer areas of the nebula. This image better shows the dark Bok globules, which are believed to be sites of star formation. These globules are about one-third of a light year and larger.

NGC4259, 4270, 4273, 4277, 4281, a cluster of galaxies in Virgo, magnitudes 11.3 to 13.6. This was taken using the f/6.3 focal reducer, giving an effective focal ratio of f/4. This is a mosaic, and a composite of 58 exposures for a total integration time of 29 minutes. It was processed with dark frame subtraction, flat fields, then compositing the left and right halves separately, then background flattening, mosaic assembly, Digital Development (FFT, low-pass, mild) and finally a contrast stretch. Images were taken between 12:09 a.m. and 2:04 a.m. on the morning of the 1st. Here is a key image identifying the major galaxies, their magnitudes and the length along their longest axis. (Note that there are at least five or six more galaxies in this field that aren't identified in my SkyMap Pro 6 software... anyone interested in making some identifications?) As an interesting aside, the area in the center where the left and right images overlap was wide enough to study as a separate image. Since the center strip was covered in both images, it ends up having an effective exposure time of 58 minutes. So this image was carved out separately, and processed with Maximum Entropy Deconvolution, Digital Development (FFT low-pass, mild) and a contrast stretch. The double- length exposure gives considerably more detail in NGC 4273, as you can see.

M4, a globular cluster in Scorpius, magnitude 5.4, diameter 35', distance is 6,800 l.y., age about 10 billion years. This quick image was taken using the f/6.3 focal reducer, giving an effective focal ratio of f/4. This is a composite of 8 exposures for a total integration time of 8 minutes. It was processed with dark frame subtraction, flat field, then compositing, Digital Development (FFT, low-pass, mild) and finally a contrast stretch. Images were taken between 2:44 a.m. and 2:59 a.m. the morning of the 1st.

NGC4361, a planetary nebula in Corvus, magnitude 10.3, diameter 1'.3. Note how easy it is to mistake this planetary nebula for a spiral galaxy! This was taken using the f/6.3 focal reducer, giving an effective focal ratio of f/4. This is a composite of 30 exposures for a total integration time of 30 minutes. It was processed with dark frame subtraction, flat field, then compositing, and finally a contrast stretch. Images were taken between 10:37 p.m. and 11:59 p.m. on the 30th. Here is another rendering of this imageof NGC 4361, adding Digital Development (FFT, low-pass, mild), and finally a contrast stretch. This image was processed to bring out more of the detail in the outer reaches of the planetary. And finally here is a third image processed with much less contrast stretch. This third image shows the central star in the planetary nebula, which shines at magnitude 13.2. These images were taken from Coyle Field in southern New Jersey.

NGC6822, an irregular galaxy in Sagittarius, magnitude 9.3, diameter 16'. This image was taken using the f/6.3 focal reducer, giving an effective focal ratio of f/4. This is a composite of 15 exposures for a total integration time of 15 minutes. It was processed with dark frame subtraction, flat field, then compositing, Digital Development (FFT, low-pass, mild) and finally a contrast stretch. Images were taken between 4:28 a.m. and 4:55 a.m. the morning of the 1st. NGC 6822 is an irregular member of the Local Group of galaxies. This object would benefit from a considerably longer exposure, and a slightly wider field of view.