Cassiopeia Observatory logo

HST-Sun Transit Dry Run;
Neptune & Uranus Moons, M31 Exposure Tests

Posted: 20 October 2016

Open: Wednesday, 19 October 2016, 1412 MST
Temperature: 104°F
Session: 1026
Conditions: Clear

Equipment Used:
12" f/8 LX600 w/StarLock
Wireless AutoStar II handset
2" 24mm UWA eyepiece
Solar Filter

Camera:
D7200 DSLR

Received an alert from CalSky of the transit of the Sun by the Hubble Space Telescope (HST) to take place Thursday afternoon, 20 October 2016. Went to the observatory Wednesday afternoon to do a dry run imaging session.

1420 MST: LX600 ON, StarLock OFF, High Precision OFF. Attached the Thousand Oaks Optical Solar Filter on the 12" telescope. Then used the "Sun as Asteroid" to GOTO the Sun. Three small sunspots were visible, 102X.

Mounted the D7200 DSLR at prime focus and did some still and video exposures as a test for the actual HST-Sun transit. This is a 1/400sec, ISO 400, exposure of a portion of the Sun where the HST will pass and showing the sunspots (left):

photo

1445 MST: ended imaging tests. 1449 MST: LX600 OFF.

Close: Wednesday, 19 October 2016, 1457 MST
Temperature: 96°F
Session Length: 0h 45m
Conditions: Clear


Open: Wednesday, 19 October 2016, 1947 MST
Temperature: 74°F
Session: 1027
Conditions: Clear

Equipment Used:
12" f/8 LX600 w/StarLock
Wireless AutoStar II handset
2" 24mm UWA eyepiece

Camera:
D7200 DSLR

After re-opening the observatory on Wednesday, the 12" telescope was powered on at 1951 MST. StarLock and High Precision were turned OFF.

1953 MST: briefly viewed Neptune, 102X, and then began setting up to image Neptune and its moon Triton. The D7200 DSLR was mounted at prime focus.

2003 MST: took this 10 seconds, ISO 6400, image of Neptune and its moon Triton:


photo
Click or tap on image for animated version

The animated version made from exposures on 18 and 19 October (click/tap on image above) shows Neptune's motion against the background stars in about 24 hours. The changing position of Triton is also evident.

2023 MST: slewed to Uranus and took this 10 seconds, ISO 6400, image of Uranus and several of its moons:

photo
Click or tap on image for animated version

The movement of the planet and moons against the background stars are obvious over the 24 hour period when viewing the animated version made from exposures on 18 and 19 October.

2026 MST: added the Optec focal reducer and began preparing to do some exposure tests using the Andromeda Galaxy (M31). High Precision was left OFF but StarLock was ON for autoguiding during the exposures. First, I did five 1 minute, ISO 3200, exposures, White Balance 4000K. Here are unedited and edited versions of a single 1 minute, ISO 3200, exposure:

Unedited, 1 minute, ISO 3200
photo

Edited, 1 minute, ISO 3200
photo

The five 1 minute exposures were stacked using Lynkeos. Here are the resulting images, unedited and edited:

Unedited, stacked (5), 1 minute, ISO 3200
photo

Edited, stacked (5), 1 minute, ISO 3200
photo

For comparison to the stacked images I took a 5 minute, ISO 3200, WB 4000K, exposure. This is an edited version:

photo

The most obvious difference, besides the color (which I could have corrected), is that the stacked version (effective 5 minute exposure) shows less noise. However, the stacked version does not show NGC206 (star association at the right) prominently whereas the 5 minute exposure does. The companion galaxy M32 (bottom) shows up well though in all the images.

I also took a 5 minute, ISO 5000, WB 4000K, exposure, edited:

photo

All things considered, I prefer longer higher ISO exposures to shorter exposures that could be stacked.

2114 MST: ended the exposure tests due to the brightening sky from the rising waning gibbous Moon.

Close: Wednesday, 19 October 2016, 2125 MST
Temperature: 67°F
Session Length: 1h 47m
Conditions: Clear


Comments are welcome using Email. Twitter users can use the button below to tweet this report to your followers. Thanks.


Previous report

Cassiopeia Observatory Home Page

Back to Top


Copyright ©2016 Michael L. Weasner / mweasner@me.com
URL = http://www.weasner.com/co/Reports/2016/10/20/index.html