Category: Astrophotography

M106 Spiral galaxy and neighbors

Messier 106 (also known as NGC 4258) is a spiral galaxy in the constellation Canes Venatici. It was discovered by Pierre Méchain in 1781. M106 is at a distance of about 22 to 25 million light-years away from Earth. It is also a Seyfert II galaxy. Due to x-rays and unusual emission lines detected, it is suspected that part of the galaxy is falling into a supermassive black hole in the center. NGC 4217 is a possible companion galaxy of Messier 106.

M106 Galaxy by Marios TsalkidisContains: NGC 4346, M 106, NGC 4258, NGC 4248, NGC 4220, NGC 4217

Characteristics
M106 has a water vapor megamaser (the equivalent of a laser operating in microwave instead of visible light and on a galactic scale) that is seen by the 22-GHz line of ortho-H2O that evidences dense and warm molecular gas.
These water vapors give M106 its characteristic purple color. Water masers are useful to observe nuclear accretion disks in active galaxies.
The water masers in M106 enabled the first case of a direct measurement of the distance to a galaxy and thereby providing an independent anchor for the cosmic distance ladder.M106 has a slightly warped, thin, almost edge-on Keplerian disc which is on a subparsec scale.

It is one of the largest and brightest nearby galaxies, similar in size and luminosity to the Andromeda Galaxy.
M106 has also played an important role in calibrating the cosmic distance ladder.
Before, Cepheid variables from other galaxies cannot be used to measure distances since they cover ranges of metallicities different from the Milky Way’s.
M106 contains Cepheid variables similar to both of the metallicities of the Milky Way and other galaxies’ Cepheids.
By measuring the distance of the Cepheids with metallicities similar to our galaxy, astronomers are able to recalibrate the other Cepheids with different metallicities, a key fundamental step in improving the distances to other galaxies in the universe.

Technical details
Sky-Watcher 80ED Pro Black Diamond
SBIG 8300M
HEQ5 Pro
Guiding : QHY5
Skywatcher .85x Focal Reducer & Corrector
Software: PixInsight,  Main Sequence Software SequenceGeneratorPro
Accessories: Starlight Xpress Starlight Xpress FW 5*2”
Resolution: 1676×1266

Dates: June 13, 2015

Frames:
Baader Blue 2″: 15×240″ -5C bin 2×2
Baader Green 2″: 15×240″ -5C bin 2×2
Baader Red 2″: 15×240″ -5C bin 2×2

Integration: 3.0 hours
Darks: ~50
Flats: ~10
Bias: ~300
Avg. Moon age: 25.75 days
Avg. Moon phase: 15.29%
Bortle Dark-Sky Scale: 2.00
Temperature: 17.50
RA center: 184.451 degrees
DEC center: 47.451 degrees
Pixel scale: 4.272 arcsec/pixel
Orientation: 176.036 degrees
Field radius: 1.246 degrees

Annotated version :

M106 Galaxy Annotated by Marios Tsalkidis

Nikon D90 in astrophotography – sensor specifications

The Nikon D90 was a very popular DSLR back in 2008 when it was released and still is a substantial camera.
Using any camera in astrophotography gets you to a point where you need various details about the sensor, in order to calculate the Field Of View with a particular lens or telescope, be able to plate solve your astro images and a lot of other things.

Interestingly there was very little in-depth information about Nikon D90 Cmos sensor and its internals in general, so here is a list of all the info i have gathered over time for the particular model.

 

Nikon D90 Body

BrandNikon
ModelD90
Effective MegaPixels12.30
Sensor dimensions23.6 x 15.8 mm
Sensor typeCMOS
Sensor resolution4281 x 2873
Crop factor1.52
Diagonal28.40 mm
Surface area372.9 mm²
Pixel pitch (size)5.51 µm
Pixel area30.36 µm²
Pixel density3.29 MP/cm²
ISOAuto, 200 - 3200 (plus 6400 with boost)
Exposure Compensation±5 EV (at 1/3 EV, 1/2 EV steps)

The sensor has a surface area of 372.9 mm². There are approx. 12,300,000 photosites (pixels) on a NIKON D90 sensor.
Pixel pitch, which is a measure of the distance between pixels. Pixel pitch tells you the distance from the center of one pixel to the center of the next. Pixel size (pitch) is essential in astrophotography.
Pixel or photosite area is 30.36 µm². The larger the photosite, the more light it can capture and the more information can be recorded.
Pixel density tells you how many million pixels fit or would fit in one square cm of the sensor. Nikon D90 has a pixel density of 3.29 MP/cm².

One shot color camera sensors are usually arranged in a specific order, one of the most well known being the Bayer pattern.

Nikon D90 Bayer pattern
Nikon D90 Bayer pattern

 

 

 

 

The Bayer pattern in Nikon D90 in case you have raw files that you need to manually de-bayer them is GBRG (Green, Blue, Red, Green)

NGC2237 Rosette Nebula in HA

NGC2237_ROSETTE_HA_FINAL_C

A quick go on this spectacular nebula, as it is currently too low on the horizon for serious light gathering.
I hope next year’s weather will allow more data!

Target details
The Rosette Nebula (also known as Caldwell 49) is a large, circular H II region located near one end of a giant molecular cloud in the Monoceros region of the Milky Way Galaxy. The open cluster NGC 2244 (Caldwell 50) is closely associated with the nebulosity, the stars of the cluster having been formed from the nebula’s matter.
The complex has the following NGC designations:
NGC 2237 – Part of the nebulous region (Also used to denote whole nebula)
NGC 2238 – Part of the nebulous region
NGC 2239 – Part of the nebulous region (Discovered by John Herschel)
NGC 2244 – The open cluster within the nebula (Discovered by John Flamsteed in 1690)
NGC 2246 – Part of the nebulous region

The cluster and nebula lie at a distance of some 5,200 light-years from Earth (although estimates of the distance vary considerably, down to 4,900 light-years.) and measure roughly 130 light years in diameter. The radiation from the young stars excites the atoms in the nebula, causing them to emit radiation themselves producing the emission nebula we see. The mass of the nebula is estimated to be around 10,000 solar masses.
It is believed that stellar winds from a group of O and B stars are exerting pressure on interstellar clouds to cause compression, followed by star formation in the nebula. This star formation is currently still ongoing.
A survey of the nebula with the Chandra X-ray Observatory in 2001 has revealed the presence of very hot, young stars at the core of the Rosette Nebula. These stars have heated the surrounding gas to a temperature in the order of 6 million kelvins causing them to emit copious amounts of X-rays.

Gear used
Sky-Watcher 80ED Pro Black Diamond
SBIG 8300M
HEQ5 Pro
Guiding camera: QHY CCD QHY5 mono
Focal reducer: Skywatcher .85x Focal Reducer & Corrector
Filters: Baader 7nm Ha 2”
Starlight Xpress Starlight Xpress FW 5*2”

Processed in PixInsight

Resolution: 1743×1380
Dates: April 12, 2015
Frames: Baader 7nm Ha 2”: 10×600″ -5C bin 2×2
Integration: 1.7 hours
Darks: ~20
Flats: ~20
Bias: ~20
Avg. Moon age: 21.98 days
Avg. Moon phase: 51.77%
Bortle Dark-Sky Scale: 3.00
Temperature: 3.00
Locations: Amarynthos obs, Amarynthos, Evia, Greece