K3's Astronomy - Comets
"When I consider your heavens, the work of your fingers, the moon and the stars which You have set in place, what is Man that You are mindful of him?" -- Psalm 8:3,4

1. Comet C/2002 C1 Ikeya-Zhang
2. Comet C/2001 A2 LINEAR

Comet C/2002 C1 Ikeya-Zhang (4.4.2002)


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Comet C/2002 C1 Ikeya-Zhang + M31, 4.4.2002 (18:44 - 19:02 UT)
Resolution: 46.20 arcsec/pixel
Camera: Vesta 675SC2 with 50mm F2 camera objective (piggy back)
Result focal ratio: F2
Exposure: 50x20s (gain 35%), 49xDF, cooling (12V)
Seeing: windy, but clear skies. Comet was too low (only 12.5° above horizon and only 8° above "shinny" block of flats),
lim.magnitude for naked eye (near comet) ~3, temperature 8.4°C
Supposed magnitude of comet: 3.9
Comet distance from Earth: 0.5512AU (82.5 mil. km)

This was the first light of my newly modified camera (cooled SC2). Darkframe contained absolutelly neither hot nor warm pixel. Because of low altitude of comet above horizon and city smog, I hardly saw M31 in my 15x50 binocular.Comet was not visible by naked eye. AVI file was captured and processed by K3CCDTools.
M32 is visible southwards from M31 and hint of M110 is north-westward from M31.

Comet C/2002 C1 Ikeya-Zhang (23.3.2002)


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Comet C/2002 C1 Ikeya-Zhang, 23.3.2002 (19:34 - 19:41 UT)
Resolution: 17.12 arcsec/pixel
Camera: Vesta 675SC with 135mm F4 camera objective (piggy back)
Result focal ratio: F4
Exposure: 15x30s (gain 80%), 30xDF
Seeing: windy, but clear skies. Comet was too low (only 12° above horizon and only 7° above "shinny" block of flats),
lim.magnitude for naked eye (near comet) ~4.5, temperature 2.5°C
Supposed magnitude of comet: 4.0
Comet distance from Earth: 0.7284AU (109.0 mil. km)

Comet visible by naked eye. AVI file was captured and processed by K3CCDTools (with flat field used). Because of strong processing hot pixels were not sufficiently eliminated. Speck on CCD chip was still present, but eliminated by using proper flat field.


Comet C/2002 C1 Ikeya-Zhang, 23.3.2002 (18:44 -19:12 UT)
Resolution: 17.12 arcsec/pixel
Camera: Vesta 675SC with 135mm F4 camera objective (piggy back)
Result focal ratio: F4
Exposure: 39x40s (gain 50%), 30xDF
Seeing: windy, but clear skies. Comet was too low (only 9° above horizon and only 4° above "shinny" block of flats),
lim.magnitude for naked eye (near comet) ~4.5, temperature 4°C
Supposed magnitude of comet: 4.0
Comet distance from Earth: 0.7282AU (111.6 mil. km)

Low position of comet above horizon, shining block of flats and soft clouds caused, that the result photo is worse than the above photo, although longer exposure was used.
AVI file was captured and processed by K3CCDTools (with flat field used).


Comet C/2002 C1 Ikeya-Zhang, 23.3.2002 (18:33 UT)
Resolution: 17.12 arcsec/pixel
Camera: Vesta 675SC with 135mm F4 camera objective (piggy back)
Result focal ratio: F4
Exposure: 4x20s (gain 80%), 30xDF
Seeing: windy, but clear skies. Comet was too low (only 13° above horizon and only 8° above "shinny" block of flats),
lim.magnitude for naked eye (near comet) ~4.5, temperature 2.5°C
Supposed magnitude of comet: 4.0
Comet distance from Earth: 0.7285AU (109.0 mil. km)

Comet visible by naked eye. AVI file was captured and processed by K3CCDTools. For the first time, the flat field was used in K3CCDTools. Because of low number of frames (4), hot pixels were not sufficiently eliminated.

Comet C/2002 C1 Ikeya-Zhang (22.3.2002)


Comet C/2002 C1 Ikeya-Zhang, 22.3.2002 (19:02 -19:17 UT)
Resolution: 17.12 arcsec/pixel
Camera: Vesta 675SC with 135mm F4 camera objective (piggy back)
Result focal ratio: F4
Exposure: 60x15s (gain 100%), 30xDF
Seeing: windy, but clear skies. Comet was too low (only 7° above horizon and only 2° above "shinny" block of flats),
lim.magnitude for naked eye (near comet) ~4.5, temperature 4°C
Supposed magnitude of comet: 4.0
Comet distance from Earth: 0.75AU (111.6 mil. km)

Sun was 23° below horizon. This was the first time, when I saw the comet by naked eyes.
AVI file was captured and processed by K3CCDTools. Unfortunately, some speck (on CCD chip) of circular shape is visible in the right part of picture (visible as dark circular spot).


Comet C/2002 C1 Ikeya-Zhang, 22.3.2002 (19:20 -19:28 UT)
Resolution: 17.12 arcsec/pixel
Camera: Vesta 675SC with 135mm F4 camera objective (piggy back)
Result focal ratio: F4
Exposure: 60x8s (gain 100%), 30xDF
Seeing: windy, but clear skies. Comet was too low (only 5.5° above horizon and only 0.5° above "shinny" block of flats),
lim.magnitude for naked eye (near comet) ~4.5, temperature 4°C
Supposed magnitude of comet: 4.0
Comet distance from Earth: 0.75AU (111.6 mil. km)

Comet C/2002 C1 Ikeya-Zhang (18.3.2002)


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here to see full resolution (1.57"/pixel) photo.
Comet C/2002 C1 Ikeya-Zhang, 18.3.2002 (17:55 -18:16 UT)
Mosaic of 4 pictures
Resolution: 4.71 arcsec/pixel
Camera: Vesta 675SC at prime focus with 0.60FR
Telescope: 8" F6 Orion Europa Newtonian
Result focal ratio: F3.6
Exposure: 3 pictures - summing about 50x6s (gain 50%), 50xDF
                1 picture - summing about 20x6s (gain 50%), 50xDF
Seeing: quite good seeing, but comet was too low (only 17° above horizon and only 12° above "shinny" block of flats),
lim.magnitude for naked eye (near comet) ~3.0, temperature ~9°C
Supposed magnitude of comet: 4.1
Comet distance from Earth: 0.82AU (123.0 mil. km)

Sun was almost 13° below horizon. The comet was easily visible in my 7x50 finder, but not visible by naked eye (urban location :-().
AVI file was captured and processed by K3CCDTools. All frames were aligned relative to comet. The stars trails reveal proper motion of comet!
Summed image was postprocessed in K3CCDTools. Vignetting on corners of frames was eliminated by creating artificial flat field frame in Corel PhotoPaint (by using radial fountain fill). The flat field was applied to each of 4 frames of mosaic (by using flat field frame as object with 'Hard Light' merge method). Brightness and color of result frames were adjusted to create the smooth mosaic. The mosaic is much more smooth than the mosaic from 8.3.2002.

Comet C/2002 C1 Ikeya-Zhang (8.3.2002)


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Comet C/2002 C1 Ikeya-Zhang, 8.3.2002 (17:48 -17:56 UT)
Resolution: 3.14 arcsec/pixel
Camera: Vesta 675SC at prime focus with 0.60FR
Telescope: 8" F6 Orion Europa Newtonian
Result focal ratio: F3.6
Exposure: summing 50x10s (gain 90%), 65xDF
Seeing: quite good seeing, but comet was too low (only 14° above horizon and only 9° above "shinny" block of flats),
lim.magnitude for naked eye (near comet) ~3.0, temperature ~7°C
Supposed magnitude of comet: 5.1
Comet distance from Earth: 1.02AU (152.5 mil. km)

Sun was almost 15° below horizon. The comet was visible in my 7x50 finder, but not visible by naked eye (urban location :-().
AVI file was captured and processed by K3CCDTools. All frames were aligned relative to comet. So during about 8 minutes of exposure the stars are visible. The stars trails reveal proper motion of comet!
Summed image was postprocessed in K3CCDTools by stretching histogram 1-100%, RGB balance and gamma factor 2.50.


Click the image to see full resolution (1.57"/pixel) photo.
The same summed image, but another postprocessing in K3CCDTools:
Histogram streching 0-40%, RGB Balance, gamma 1.50.
This image is "more linear", because of lower value of gamma. The comet's nucleus is more overexposed (by stretching histogram top level to 40%), but details in tail are more visible, in comparison with above picture.

Click the image to see full resolution (1.57"/pixel) photo.
Comet C/2002 C1 Ikeya-Zhang (tail area), 8.3.2002 (17:59 -18:04 UT)
Resolution: 3.14 arcsec/pixel
Camera: Vesta 675SC at prime focus with 0.60FR
Telescope: 8" F6 Orion Europa Newtonian
Result focal ratio: F3.6
Exposure: summing 28x10s (gain 90%), 65xDF
Seeing: quite good seeing, but comet was too low (only 13° above horizon and only 8° above "shinny" block of flats),
lim.magnitude for naked eye (near comet) ~3.0, temperature ~7°C
Supposed magnitude of commet: 5.1

Only 3 minutes after taking photo of comet's nucleus I started to capture comet's tail area.
Interesting thing was alignment. As tail in AVI frames was faint, the only available alignment point were stars. So at first I aligned frames relative to stars. Then I calculated length of star trails in photo above (shift in x, y). The shift I divided by number of frames. Then I calculated the result shift for 28 frames of tail area. I manually shifted these frames (all work was done in K3CCDTools).
The result of summation was postprocessed in K3CCDTools by stretching histogram 1-100%, RGB balance and gamma factor 1.70 (the sky above block of flats was brighter, so I could not afford to use gamma 2.50).


Click the image to see full resolution (1.57"/pixel) photo.
Example of using stronger histogram stretching (1-40%, gamma 1.00). This picture is result of alignment relative to stars (not to comet).
The glow in the upper left corner is probably caused by glowing CCD amplifier (I have SC1 modified webcam, so far).

Click the image to see full resolution (1.57"/pixel) photo.
Comet C/2002 C1 Ikeya-Zhang, 8.3.2002 (17:48 -18:04 UT)
The mosaic from above photos.
It was interesting to "paste together" two photos. At first I aligned frames according to 2 stars (visible in the centre of mosaic). Then I realised, that stars of the left frame were captured later, than the stars of the right frame, so they must be shifted to bottom right concerning the stars trails of the right frame.
The result image was not retouched, to show the real picture, as it was captured by webcam. Brightness differences between frames are caused by alternating light polution.

Comet C/2001 A2 LINEAR (12.7.2001)

During my holiday I tried to get a photo of comet C/2001 A2 LINEAR. I recorded the sky near the comet with my SONY Video8 camcorder to Video8 tape. When I returned home, I captured the video from tape to computer and processed it (with applying dark-frame) with my K3CCDTools program. Here are results:

Comet C/2001 A2 LINEAR,
12.7.2001, 23:30 (21:30 UT)
Map generated with SkyMap Pro 7 Demo. Click the map to see the map in 100% size.

Integration of 1003 frames + histogram functions with K3CCDTools. Hard processed in Corel PhotoPaint.

The same as on the left, but no processing in Corel PhotoPaint

The negative of the above photo.
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The negative of the above photo.
Place mouse pointer above the photo to see the labels.

Another processing of 1003 frames with K3CCDTools. The black level was kept on zero value, so the sky background is not black. No other processing.
 

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Last Update: 04.04.2002