Photos by Roger

11/4/10 Comet Hartley 2

Date: 11/4/2010

Location: Tierra Del Sol, California


Conditions: 0% moon, seeing 5/10, transparency 3/10, temperature 55 F, wind 8-15 mpg.

Telescope: Canon 24-105mm L series lens, 60mm @ f4, mounted on Kirk ball head.

Guiding: none (this mount does have a guide port)

Mount: AstroTract, provided polar scope used to polar align.

Camera: Canon EOS 7D

Focusing: Manual on Jupiter. LIVE FOCUS with 10x magnification used on camera viewer.

Exposures: lights: (2) 5 min raw 800 ISO, (0) darks, (0) bias, (0) flats .

Processing: Images Plus 3.82 - Used automatic image set processing to convert raw to a fits file, normalized, aligned, and combined using min-max, performed digital development, color saturation & brightness, gradient removal, smoothing, cropping, converted to JPEG. Use Photoshop CS5 for final sharping and optimizing for web.


Comments: This was the first night I used my AstroTract mount. I am quite happy with the tracking and my polar alignment was not bad. This is going to be a great small pick up and go mount for imaging wide field and some deep sky objects with my Canon 7d and the associated lens I have with it. Finding deep sky objects in the view finder however is very challenging.

12/5/07Comet 17P/Holmes

Date: 12/5/2007
Location: Tierra Del Sol, California
Conditions: 0% moon, seeing 4/10, transparency 6/10, temperature 55-65 F, very dry night, wind 5-20 mpg.

Telescope:Canon 70-200mm L series lens, piggy backed on side by side.

Guiding: TV85, 600mm, F7, prime focus, no diagonal, camera The Images Source 24AF04.AS, PHD software

Mount: Losmandy G11, Gemini goto, polar scope used to polar align.

Camera: Canon EOS 40D

Focusing: Manual on star Mirfak using LIVE FOCUS viewing done on laptop using Canon Utility software.

Exposures: lights: (6) 5 min raw 800 ISO, (6) 3 min raw 800 ISO, (6)1.5 min raw 800 ISO,(6) darks raw, (6) bias raw, (6) flats raw.

Processing:IP 3.0 - converted raw to FITS, dark flat, & bias frame calibrated, centroid 2 pt align-rotate, combined min-max, digital development, convert to 16 bit TIFF, PS CS , white balance, neutralize sky, black balance, color enhance, highlights enhance, converted to JPEG for web.
Comments: This comet is a lot bigger since 11/2/2007. It is so huge that it covered about half of the frame. The open cluster below the comet is NGC1245, magnitude 7.7, 10' diameter.
11/2/07Comet 17P/Holmes

Tierra Del Sol, California, Celestron C8, .63 focal reducer, prime focus, Canon 40d, used live mode view finder zoomed to 10x to focus on nearby star Mirfak,1 raw exposure, 25 sec, daylight WB, processed in IP2.82 and Photoshop CS. It is so huge that it covered about half of the frame. K3C
11/1/2007 Comet 17P/Holmes

Tierra Del Sol, California, TV85, prime focus, Canon 40d, used live mode through laptop to focus on nearby star Mirfak, 15 raw exposures, 12 to 25 sec, daylight WB, aligned, combined, and processed in IP2.82 and Photoshop CS
Comet 17P/Holmes - Trajectory

The comet's retrograde path in Perseus during July 2007 & March 2008. (Dates given every 14 days) It may be large for some time yet but no one knows what it will do. It will be lots of fun to see what happens.

11/3/2007 Comet 17P/Holmes - Orbit
Comet 17P/Holmes was discovered by Edwin Holmes on November 6, 1892 while he was conducting regular observations of the Andromeda Galaxy (M31). Its discovery in 1892 was made because of and during magnitude changes similar to the 2007 outburst. 17P/Holmes brightened to an approximate magnitude of 4 or 5 before fading from visibility over a period of several weeks.

Between October 23 & 24, 2007, Comet Holmes grew much brighter, going from magnitude 17 to magnitude 2.5 in just a few hours. The first person reportedly to notice a change was J. A. Henríquez Santana on Tenerife in the Canary Islands minutes later Ramón Naves in Barcelona noticed the comet at magnitude 7.3. It became easily visible to the naked eye as a bright yellow "star" in Perseus, and by October 25 17P/Holmes appeared as the third brightest "star" in that constellation.

While large telescopes showed fine-scale cometary details, naked-eye observations gave a view similar to that of a star until October 26th. After that date, 17P/Holmes began to appear more comet-like to naked-eye observers. During the comet's outburst, its orbit took it to near opposition with respect to Earth, and since comet tails point away from the Sun, Earth observers were looking nearly straight down along the tail of 17/P Holmes, making the comet appear as a bright sphere.

Based on orbital computations and luminosity before the 2007 outburst, the comet's nuclear diameter was estimated at 3.4 km. In late October 2007 the coma's diameter increased from 3.3 arcminutes to over 13 arcminutes], about half the diameter that the Moon subtends in the sky. At a distance of around 2 AU, this means that the true diameter of the coma swelled to over 1 million km or about 70% of the diameter of the Sun. By comparison, the Moon is 380,000 km from Earth. Therefore, during the 2007 outburst of Comet Holmes the coma was a sphere wider than the diameter of the Moon's orbit around Earth.

Last updated on November 14, 2010