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Galaxy Messier 101, Pinwheel Galaxy

Object :	M101, Pinwheel galaxy
Coordinates/Direction :	RA: 14h03m, DEC: +54o20'
Object size :	28.8' x 26.9'
Apparent magnitude :	7.8
Distance :	21.6 Mly
No solar mass :	1e12
Type :	SAB
Discovered by :	Pierre Mechain, year 1781
Find in constellation :	Ursa Major
More to know :	Wikipedia: https://en.wikipedia.org/ wiki/ Pinwheel Galaxy

M101 2025-12-29, crop (Click on image and get a full resolution in a new window)

Date :	2025-12-29
Time (UT) :	22:03 - 02:00

Exp. time :	77x120 seconds, 400iso, every third dithered
Image process tool :	Siril, Graxpert, VeraLux, Gimp, Irfanview
Processing :	calibration flat and photometric color, background subtraction, stretch
Weather :	Clear sky, Moon phase 72%, Temperature -1o

Comment :

The Pinwheel galaxy is very exiting and it's relative bright with its magnitude of 7.8. I now have my big refractor up and running, three times the focal length compare to earlier lens. I got 154 minutes of exposure in a single night, from my place is hard to get more than 2 hours because of the surrounding houses.

M101 2025-03-19, crop (Click on image and get a full resolution in a new window)

Date :	2025-03-19
Time (UT) :	22:48 -  00:10

Exp. time :	60x60 seconds, 400iso, every third dithered
Image process tool :	Siril, Gimp, Irfanview
Processing :	bias, flat and photometric color calibrated, crop 800x800 pix 1:1 scale
Weather :	clear sky, Moon phase 78%, temperature +7o C

Comment :

This night was a big moment, first test of the new OnStep driver for the EQ6 mount. Auto guider now is on the total error 0.6" - 0.8". The focus isn't as good as usual.

M101 2025-01-25 + 01-26, mosaic (Click on image and get a full resolution in a new window)

Date :	2025-01-25 + 2025-01-26
Time (UT) :	22:26 - 01:10

Exp. time :	2x 60x60seconds, iso1600, every third dithered, 2x1 mosaic
Image process tool :	Siril, Gimp, Irfanview, Astap
Processing :	flat, photometric color calibrated, stitch of mosaic
Weather :	clear sky, Moon phase 18%, temperature +0o C

Comment :

My friend has been taken mosaics for a while now, inspired by that I prepare to take my own. Even if my 300mm lens at full frame is wide there are nebulas that are wider, NGC7000 is one of them. To practice I take the first photographies from my balcony, aim at the galaxy M101. I only have a narrow free view and limit the mosaic to 2x1, about 12x4.5' 13354x5478 pixels. KStars/Ekos that I use has a built in mosaic tool, just point to the object and tell how big mosaic you want. I also had to find a tool to stitch these huge 500MB 32-bit fits files. Long time ago I used Astap, an advanced astronomy image processing tool. Now I installed it again, the only free software I found that could handle 32-bit fits images aimed for astronomy images. It was very easy to use, almost like push a button and wait. Here is a plate solved image if you want to know what objects there are around the galaxy M101: M101 plate solved

M101 2024-01-07 + 02-03 + 02-17 + 02-23, crop (Click on image and get a full resolution in a new window)

Date :	2024-01-07 + 02-03 + 02-17 + 02-23
Time (UT) :	-

Exp. time :	118x120 seconds = 3 hours 56 minutes, iso1600, every third dithered
Image process tool :	Siril, Gimp, Irfanview
Processing :	bias, flat and photometric color calibrated, crop 800x800 pix 1:1 scale
Weather :	clear sky, full Moon, temperature +3o C

Comment :

Collected the photos I have got from January to February this year and got almost 4 hours of exposure time. Much better but still need more exposure or filters to reduce the light pollution.

M101 2024-02-23, crop (Click on image and get a full resolution in a new window)

Date :	2024-02-23
Time (UT) :	20:18 to 21:24

Exp. time :	25x120 seconds = 50 minutes, iso1600, every third dithered
Image process tool :	Siril, Gimp, Irfanview
Processing :	bias, flat and photometric color calibrated, crop 800x800 pix 1:1 scale
Weather :	clear sky, full Moon, temperature +3o C

Comment :

One more image on the galaxy, this time 50 minutes. Sooner or later I stack all my images of it together to reduce the noise.

M101 2024-02-17 crop (Click on image and get a full resolution in a new window)

Date :	2024-02-17
Time (UT) :	19:24 to 20:33

Exp. time :	25x120 seconds = 50 minutes, iso1600, every third dithered
Image process tool :	Siril, Gimp, Irfanview
Processing :	bias, flat and color calibrated
Weather :	clear sky, Moon, temperature -1o C

Comment :

One more image on the galaxy, this time 50 minutes. Sooner or later I stack all my images of it together to reduce the noise.

M101 2024-02-03 crop (Click on image and get a full resolution in a new window)

Date :	2024-02-03
Time (UT) :	22:21 to 00:06

Exp. time :	39x120 seconds, iso1600, every third dithered
Image process tool :	Siril, Gimp, Irfanview
Processing :	bias, flat and color calibrated
Weather :	clear sky, no Moon, temperature -4o C

Comment :

One galaxy in our local group, the fov of it is about as the Moon. Must have at least 2 hours of exposure, but more is even better.

M101 2023-02-27 crop

Date :	2024-01-07
Time (UT) :	23:28 to 00:38

Exp. time :	30x120 seconds, iso1600, every third dithered
Image process tool :	Siril, Gimp, Irfanview
Processing :	resize, level, cal dark&flat
Weather :	clear

Comment :

M101 is a galaxy that has a relative big angular size, still it's very small. My bigger refractor helps to reveal the details, three times the focal lenght.

M101 2023-02-27 (click on the image to get a full resolution photo in a new window)

Date :	2023-02-27
Time (UT) :	20:25 to 21:04

Exp. time :	30x60 seconds, iso1600, every third dithered
Image process tool :	Siril, Gimp, Irfanview
Processing :	resize, level, cal dark&flat
Weather :	clear

Comment :

In February there are not so many exiting objects to observe from our balcony. It's the old friend M101 who is in focus again. What to say, I need a bigger telescope and lot of exposure times.

M101 2021-02-15 (click on the image to get a full resolution photo in a new window)

Date :	2021-02-15
Time (UT) :	21:31 to 23:14

Exp. time :	92x30 seconds, iso800, in dithering mode
Image process tool :	AstroImageJ, Fitswork, Irfanview
Processing :	resize, level, cal dark&bias, no flat cal
Weather :	clear

Comment :

This is first light with my new Pentax medium format 300 mm lens. To be that old it's relative advanced with its ED lenses and have a good reputation of quality. The galaxy isn't easy to see. Click on the image to get a full size image of it. Look at the corners and how it focus the stars. Looks very good but at the upper left corner the stars are a bit elongated. The galaxy is the little weak blob at center. At f/4 it collect photons much quicker than my f/7 telescope. About three times, 45 minutes exposure with this lens correspond to140 minutes with the telescope. This time I didn't flat filed correct the image. It takes some time for me to make a correct master Flat for this new lens. But this lens has very low vignetting even when used on a full frame camera, that is the idea behind to use medium format lenses. This old lens is a wonderful set of glasses, this will be my standard lens in the future at the 300 mm range.

M101 2019-01-18

Date :	2019-01-18
Time (UT) :	23:38 to 00:18

Exp. time :	60x30 seconds, iso1600, dithering mode
Image process tool :	AstroImageJ, Fitswork, Irfanview
Processing :	resize, level, cal dark&bias
Weather :	clear

Comment :

Little bit better but still need a lot more exposure. The problem the limited free view from my balcony don't let me take enough photos.

M101 2018-02-05

Date :	2018-02-05
Time (UT) :	21:29 to 22:25

Exp. time :	57x30 seconds, iso800, dithering mode
Image process tool :	AstroImageJ, Fitswork, Irfanview
Processing :	resize, level, cal dark&bias
Weather :	clear

Comment :

This photo has to much noise because it's only a 7.8 magnitude galaxy. More exposure time needed.

M101 2018-01-06, new setup with longer focal length

Date :	2018-01-07
Time (UT) :	00:33 to 01:40

Exp. time :	46x60 seconds, iso800, dithering mode
Image process tool :	AstroImageJ, Fitswork, Irfanview
Processing :	resize, level, cal dark&bias
Weather :	clear

Comment :

This photo has to much noise because it's only a 7.8 magnitude galaxy. More exposure time needed.

M101 2015-12-08

Date :	2015-12-08
Time (UT) :	00:17 to 01:25

Exp. time :	31x120 seconds, iso800, dithering mode
Image process tool :	DSS, Fitswork, Irfanview
Processing :	resize, level, cal dark&bias flat
Weather :	clear

Comment :

This photo has to much noise because it's only a 7.8 magnitude galaxy. More exposure next time needed.

M101 close up

Object :	M101
Comment :	Here is a zoom in on the M101, FOV about 25'x25'.

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