Celestial hemisphere:  Northern  ·  Constellation: Ursa Major (UMa)  ·  Contains:  M 101  ·  NGC 5457  ·  NGC 5477
M 101 : UHC filter, 


M 101 : UHC filter
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M 101 : UHC filter

Acquisition details

Feb. 19, 2015
26×170(1h 13′ 40″)
1h 13′ 40″
Avg. Moon age:
0.58 days
Avg. Moon phase:

Basic astrometry details

Astrometry.net job: 547671

RA center: 14h03m31s.4

DEC center: +54°2251

Pixel scale: 1.017 arcsec/pixel

Orientation: 10.297 degrees

Field radius: 0.537 degrees

Resolution: 620x582

File size: 313.3 KB

Locations: La Gueule du Loup (Malonne), Namur, Namur, Belgium


Another exhibition of this learning process !

Yesterday, we had a clear night with good seeing (4) and an atmospheric resolution of 1.21 arc second.

So, along with IC 1805, a brand new framing of M42 and some extra frames for M78, I decided to go further and experiment with M 101.

This picture is a combination of the first session (0-III filter and broadband, under polluted sky, it is delivering a very poor color balance ) and a new set of frames - next version, for this combination, I will re-open the subs of the first session instead of using the noisy finished "master" and stack it on these new frames :

UHC filter =

2x 210 sec,

2x 220 sec,

1x 360 sec, all @6400iso

Broadband =

4x 54 sec

RULE N°462 : under light polluted sky, no need to push the iso and exposure time in broadband acquisition. Only yellow-white sky will be the result !

RULE N°463 : not so much oxygen 3 in our universe :-)

Learning process !


Sky plot

Sky plot


M 101 : UHC filter,