Astronomy, Photography and Weather

General Category => Astronomy & Space => Topic started by: brianb on December 03, 2010, 08:52:01 am



Title: Two Crescents - 01 Dec
Post by: brianb on December 03, 2010, 08:52:01 am
Venus and the Moon captured in morning twilight on December 1st.

(http://i885.photobucket.com/albums/ac55/bjb11213/2010/December/01/Venus-101201-0750-R-FLTX25.jpg)
0750 UT.  William Optics FLT 110, W29 (deep red) filter, 2.5x Powermate, DMK21

Diameter 42.2". Phase 23.8%. Altitude 15.39 deg.

(http://i885.photobucket.com/albums/ac55/bjb11213/2010/December/01/Moon-101201-0720-0732-R-FLTX2-mosaic07-small.jpg)
0720 - 0732 UT. William Optics FLT 110, W29 (deep red) filer, 2x Powermate, DMK41; 7 frame mosaic, 24% resize. A full size version can be viewed here (http://s885.photobucket.com/albums/ac55/bjb11213/2010/December/01/?action=view&current=Moon-101201-0720-0732-R-FLTX2-mosaic07.jpg) (select "high res image" from the zoom menu).

Diameter 32' 39.6". Colongitude 210.5 deg. Age 25.07 days. Illumination 23.7%. Libration in latitude +07 deg 25 min; libration in longitude +01 deg 52 min. Altitude 20.75 deg.

Note the very similar phases! However the size is very different...

Here's a crop of the Aristarchus area from the full size image; allowing for the difference in pixel pitch between the DMK21 & DMK41 cameras (5.6 microns and 4.65 microns respectively) this is almost exactly the same image scale as the Venus image at the top of this post.

(http://i885.photobucket.com/albums/ac55/bjb11213/2010/December/01/Moon-101201-0720-0732-R-FLTX2-mosaic07-crop.jpg)

Transparency good. Seeing poor to bad with substantial boiling. Temperature 0C; wind E force 3; baro 1020 mb, steady.


Title: Re: Two Crescents - 01 Dec
Post by: rjgjr on December 03, 2010, 04:07:11 pm
Excellent images as usual Brian, beautiful mosaic of the Moon. Love the long shadows on the crop.


Title: Re: Two Crescents - 01 Dec
Post by: jjb on December 03, 2010, 10:22:36 pm
Good images Brian nice detail.


Title: Re: Two Crescents - 01 Dec
Post by: markt on December 04, 2010, 10:03:02 am
Brilliant images as usual Brian!

What is the difference in image scale between the 21 & 41 not allowing for the pixel pitch of the 2 cameras?  Curious about this...


Title: Re: Two Crescents - 01 Dec
Post by: brianb on December 04, 2010, 12:53:15 pm
Quote
What is the difference in image scale between the 21 & 41 not allowing for the pixel pitch of the 2 cameras?
The DMK21 has 5.6 um pixel pitch, the DMK41 has 4.65 um pixel pitch.

WO FLT 110 focal length is 770 mm.

With x2 Powermate, 1540 mm: DMK41 image scale is 0.617861 arc sec per pixel

With x2.5 Powermate, 1925 mm: DMK21 image scale is 0.595273 arc sec per pixel

Or if you prefer 2.5 / 2.0 is approximately equal to 5.6 / 4.65

The image scale with DMK41 & 2x Powermate is very nearly the same as the image scale with DMK21 and 2.5x Powermate.


Title: Re: Two Crescents - 01 Dec
Post by: markt on December 05, 2010, 10:47:27 am
Thanks for that Brian!  :)


Title: Re: Two Crescents - 01 Dec
Post by: martinastro on December 05, 2010, 05:05:56 pm
These are outstanding Brian!, the lunar detail is exceptional and the crescent phase of Venus is beautiful. Congrats on such a rewarding photo session.