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Jupiter, Spectra, Comet C/2012 S1 ISON

Posted: 3 January 2013

Clouds returned to Oracle skies during the day on Tuesday, 1 January 2013. Cassiopeia Observatory was opened for the first session in 2013 on Wednesday, 2 January, at 1815 MST, 48°F, to clear skies. At 1821 MST, viewed Jupiter, 77X, with the 8" LX200-ACF. There were "five" moons visible. Well, actually, the "fifth" moon was a bright star masquerading as a Jovian moon. I took this image of Jupiter and the "five" moons, D7000 DSLR, prime focus, "hat trick", ISO 200:


Compare it to this display from Pocket Universe on the iPhone:


The extra "moon" is near Callisto.

I then began trying to image the disk of Ganymede. The D7000 DSLR was mounted for eyepiece projection using the OPT Camera Adapter with a 9mm eyepiece (222X) and 9mm + 2X Barlow Lens (444X). I did HD video for 60 seconds at 1/30sec, using ISO settings of 1600, 3200, and 6400. My intention was to stack the best video to hopefully show the moon's disk, which was visible at 206X with the eye. Unfortunately, seeing was very bad this night and none of the videos were good enough for stacking. I was able to get this stack of Jupiter using 1138 frames from the ISO 3200 video:


The Great Red Spot is just visible near the central meridian. The poor seeing made for a poor image.

I then set up for spectrum imaging of several stars using the Star Analyzer 100 at prime focus. All of these were taken using the "drift method", 5 seconds, ISO 200 (except for Mira, which was taken at ISO 3200).

Aldebaran - Spectral Type K5

Mira - Spectral Type M5

Betelgeuse - Spectral Type M2

Alnitak - Spectral Type O9

Rigel - Spectral Type B8

The poor seeing tended to blur out the lines.

At 2023 MST, I began making preparations to try to image Comet C/2012 S1 ISON, currently at about Magnitude +16 and very small. This comet might (or might not) become as bright as the Full Moon in November 2013. I used SkySafari Pro 3.7.1 on the iPhone 4 to get the RA/Dec of the comet. I mounted the D7000 DSLR at prime focus of the 8" telescope using the Off-Axis Guider. I did a focus test image on the star Pollux using the Bahtinov Mask. I slewed the telescope to the position of the comet and located a very faint guide star. Using averted vision to keep the star centered in the illuminated reticle eyepiece, I began a 10 minute, ISO 6400, guided exposure at 2112 MST. The image, showing the entire field-of-view, has several faint galaxies visible (especially in the full-size version). The suspected comet is marked and shown in the magnified inset.


I hope to acquire two more images on the next session, one at the same RA/Dec as the above image and the other at the comet's current RA/Dec. I'll use those images to confirm the identification of Comet C/2012 S1 ISON. I plan to image the comet once each month for the next several months to show any changes.

By 2130 MST, a strong breeze was blowing. I decided to call it a night. Prior to shutting down the telescope, I took a quick look at the double star Castor, 77X.

The observatory was closed at 2148 MST, 43°F.

Comments are welcome; use the Comments section below, or you can Email Me. Thanks.

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