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elpajare

Some galaxies in Virgo

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NGC4281 and many others...

Do you think the resolution is sufficient and enough galaxies have been captured to consider it an acceptable combination of telescope / camera?

I would be happy to know your opinions

TSO RC 8" + Risingcam IMX294+ Risingsky software

10x25" + DFC+ Startools

930318442_NGC4281Y4273GXVIRGO10X25RC8IMX294.thumb.jpg.ca9bc6ebf3212868f232317c50bcbbef.jpg

 

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I think that’s a difficult question because there’s a lot of variables. Not only in personal preference but interest location and sky quality. Also if you are more interested in the galaxy group or individual galaxies  

Looking on astronomy tools for a rough sense check (I assume the scope is the 1624mm tso rc), with the 294 you’re slightly under sampling in excellent seeing but good in normal and ok seeing. Slightly over sampling in bad seeing.

My preference is always to oversmaple and bin if necessary but on paper that seems a pretty good combo. If you have good dark skies and seeing then a larger aperture and longer focal length might get you more detail, similarly a sensor with smaller pixels might get you more detail. 

For me I have the asi294pro on a 6” f4 and like it. It’s one of the more sensitive OSC cameras. It is a relatively good sized sensor that gives you zooming options in for some more detail and generally the pixel size is ok for my seeing. I tend to use if for more extended objects and larger brighter galaxies and I’m likely to be oversampling with my seeing most of the time even on the 6”.

What was the genesis of the question? What are you looking for more generally?

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Posted (edited)

Also — just thinking @elpajare @Grant — should this maybe be moved to the new Eeva discussions forum? It is looking rather empty at the moment and this is a tech discussion question. It could be the first topic!

Edited by London_David

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David, thank you for your valuable comment
I use three telescope combinations with this chip, the IMX294 to simplify material and expenses. In my house I have too many telescopes and cameras that I no longer use for EEVA. I'm in a Bortle 4-5 zone.

My combinations are:

TSO RC 8 "(1624 mm) + IMX 294 for galaxies, planetary nebulae without filters and for globular clusters with a UV / IR filter

TSO RC 6 "(1370 mm) + IMX 294 for single stars and open clusters with UV / IR filter

TSO APO 3 "(432 mm) + IMX 294 for bright nebulae with or without UHC filter according to types.

I do not know what you think and I would also like to know your opinions and advice

PS: I think it's good to move the post to the thread that says David

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First, I think that is a very good shot for the exposure given that you are using a colour sensor. The colours of the galaxies are very subtle and 'clean'. I'm surprised there is  not a little more colour variation across the star field but perhaps they are over-exposed or maybe the stretch you are using isn't preserving star colour distinctions. But I would be very happy with the result.

Concerning whether enough galaxies have been captured, it depend whether you are talking about a wider FOV or depth of penetration? Looking closely at your image I can see quite a few faint fuzzy blobs that I imagine are galaxies. It would be interesting to identify them and their magnitudes. In the middle of the triangle of the 3 main galaxies I can see a mag 17.8 galaxy for instance (PGC 1283020). I suspect there are fainter galaxies present but maybe beneath the background level you've chosen? I tend to allow in more background and allow my eye-brain combination to pull faint non-noise detail out.

Regarding over/under/critical sampling, I'm almost always under-sampled, but it is not often too noticeable at least to the extent of seeing blocky stars (others may disagree!). I think the smoothing caused by stacking and mount movement has a corrective action (while perhaps also destroying fine detail). I rarely seem to have very good seeing here -- usually above 2.5". I think David's point about being oversampled and then binning is a good one and certainly the strategy I would choose if I had a small pixel sensor. Apart perhaps from download times there is no real downside given how cheap storage is, so long as you use binning/ROI selectively where necessary, and then purely to get access to a wider variety of near real-time processing options.

Martin

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Thank you very much for your always argued opinion.
Indeed the stars are overexposed because the main object is the galaxy and it needs more exposure to be able to see well. I do not know if I can disguise something with the porsprocessed, it's one thing I have to investigate.
What I am looking for in my observations is to make a celestial map of objects of magnitude 12 or less, I do not look for weak objects, but they also appear in the photos, but I like that they have better to give depth to the subject.
The RC 8 "gives a slightly better resolution than the SKW Quattro combined with the IMX294 but only on some concrete days with good seeing, the normal thing in my observation post is between 1 and 1.5 arc sec according to Meteoblue. I can not complain.

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On 31/03/2019 at 08:43, elpajare said:

consider it an acceptable

Do you accept it ?  Yes then its great - No ok needs more work and open to input/opinions as you have done

You can always take another image another day using different combinations until you are satisfied or it meets your mapping requirements.

Personally I think it looks good ,shows many different objects , I can tell what they are and as Martin says "especially with a colour sensor".

Like the song song says - "The record shows I took the blows And did it my way" 

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NGC 4030 is a 10th magnitude Spiral Galaxy appearing in the constellation Virgo. It is 89 million light years from our solar system.

TSO RC 8" + Risingcam IMX294+ Risingsky software

10x25" + DFC+ Startools

 

 

NGC 4030 GX VIRGO 10X25 RC8+IMX294.jpg

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Some information from Wikipedia: The radio continuum emission along the galaxy's major axis is asymmetrical, being brighter in the southwestern part than in the northeast. But the overall radio surface brightness is on the low side. In the mid-infrared range, the spectrum shows indications of high ionization levels usually associated with an active galactic nucleus. However, optical observations show no signs of an active nucleus, which may just mean it is heavily obscured. Indeed, the amount of ionized matter appears to increase near the core. Although this galaxy lacks a bulge that could supply mass to a supermassive black hole, a large black hole was detected at the core by the Chandra X-ray Observatory in 2012. It is inferred to have a mass of around 104 to 105 times the mass of the Sun. This makes it one of the lowest mass nuclear black holes known

In the photo you can see three blue spots to the SW that match the description ( and Wikipedia photo) as well as the barred structure of the galaxy. NGC 4178 belongs to the Virgo supercluster and is moving away from us at 375 Km / sec

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NGC 4178 GX VIRGO 10X25 RC8+IMX294.jpg

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Hi, Enjoyed the post and the helpful thoughts from others. Just had a delightful time reading your info on the objects and then doing additional reading. When I had a 500mm Dob these objects were never seen in the detail you have captured.

Mike

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Thank you for your kind comments

They are the result of the combination TSO RC8 "+ IMX 294 that of the exposure time that are only 10 stacks of 25" each. The subsequent treatment with Startools only reveals what the catch already has

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Posted (edited)

NGC 4261 is an E2 elliptical galaxy paired with NGC 4264. NGC 4261 is the larger and brighter of the two galaxies. It has a fairly bright core that is concentrated into a nonstellar nucleus. NGC 4261 is the radio source 3C 270.

NGC 4269 is a 13th magnitude Spiral Galaxy appearing in the constellation Virgo. It is 102 million light years from our solar system.

NGC 4260 is a 11th magnitude Spiral Galaxy appearing in the constellation Virgo. It is 118 million light years from our solar system.

PGC 39565 is a 16th magnitude Elliptical Galaxy appearing in the constellation Virgo. It is 126 million light years from our solar system......and some other fuzzies

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NGC 4260+4264+4269 Y 4261 GX VIRGO 10X25 RC8+IMX294.jpg

NGC 4260+4264+4269 Y 4261 GX VIRGO 10X25 RC8+IMX294 INV.jpg

Edited by elpajare
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Posted (edited)

NGC 4294 is a barred spiral galaxy with flocculent spiral arms located about 55 million light-years away  in the constellation Virgo. The galaxy was discovered by astronomer William Herschel on March 15, 1784 and is a member of the Virgo Cluster.NGC 4294 appears to be undergoing ram-pressure striping edge-on.

NGC 4299 is a spiral galaxy located about 55 million light-years away in the constellation Virgo. It was discovered by astronomer William Herschel on March 15, 1784 and is a member of the Virgo Cluster. NGC 4299 forms an interacting pair with NGC 4294.  Wikipedia

Note: RC was a little uncollimated and it was a bit windy. Better next time...sorry

NGC 4294+4299 GX VIRGO 10X25 RC8+IMX294.jpg

Edited by elpajare
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Posted (edited)

Long-slit optical spectra show that the northern member (NGC 4496 A) of the binary galaxy VV 76 has a systematic velocity of cz = 1700 km s-1, whereas the southern member (NGC 4496 B has the considerably higher velocity of cz = 4510 km s-1. A series of three narrow-band CCD images confirms the presence of two distinct redshift systems, showing that the galaxies form an optical, rather than a physical, binary. The authors also discovered, quite serendipitously, and old type II supernova (SN 1988M) in NGC 4496 B. If NGC 4496 B were a physical companion of NGC 4496 A, SN 1988M should have been quite bright at maximum. The fact that it was not detected earlier argues against the hypothesis of discordant redshifts.

TSO RC 8" + Risingcam IMX294+ Risingsky software

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NGC 4496 A Y B IAG GX VIRGO 10X25 RC8+IMX294.jpg

Edited by elpajare
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In 1912, M 104 became the first galaxy for which a large redshift was found, by Vesto Slipher of Lowell Observatory. M 104's redshift corresponds to a recession velocity of about 1100 km/sec - too fast for it to be an object inside our Milky Way galaxy. Slipher's observations were among the first key pieces of evidence for of the expansion of the universe and the Big Bang Theory. 

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M 104 SOMBRERO GX VIRGO 10X20 RC8+IMX294.jpg

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NGC 4902 is a 11th magnitude Spiral Galaxy appearing in the constellation Virgo. It is 124 million light years from our solar system.

NGC 4902 appears roughly 2.6 x 2.4 arcminutes in size, corresponding to a physical diameter of 95292 light years. It is a spiral galaxy of morphological type Sb, and is receding at 2631 kilometers per second - about 0.9% of light speed.

In 1991 a supernova was discovered:

SUPERNOVA 1991X IN NGC 4902

Robert McNaught, Anglo-Australian Telescope, informs us of the visual discovery of a
supernova in NGC 4902 by AAVSO member Robert O. Evans, Hazelbrook, Australia.
The discovery was made on May 5.49 UT at visual magnitude 13.5-14. The supernova
is offset from the nucleus of the galaxy 13.9" east, 10.7" north.

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NGC 4902+4887 GX VIRGO 10X25 RC8+IMX294.jpg

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NGC 4781 is a 11,39 th magnitude Spiral Galaxy appearing in the constellation Virgo. It is 40 million light years from our solar system.

NGC 4781 appears roughly 3.7 x 1.5 arcminutes in size, corresponding to a physical diameter of 42996 light years. It is a spiral galaxy of morphological type Scd, and is receding at 1262 kilometers per second - about 0.4% of light speed.

TSO RC 8" + Risingcam IMX294+ Risingsky software

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NGC 4781+4784+4790 GX VIRGO 10X25 RC8+IMX294.jpg

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NGC 4713 is a 11,7th magnitude Spiral Galaxy appearing in the constellation Virgo. It is 48 million light years from our solar system.

NGC 4713 appears roughly 1.7 x 1.5 arcminutes in size, corresponding to a physical diameter of 23153 light years. It is a spiral galaxy of morphological type Scd, and is receding at 651 kilometers per second - about 0.2% of light speed.

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NGC 4713 GX VIRGO 10X25 RC8+IMX294.jpg

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NGC 4939 has been characterised as a Seyfert galaxy, a galaxy category which features bright point-like nuclei. NGC 4939 is a type II Seyfert galaxy. Its X ray spectrum is more consistent with a Compton-thick cold reflection source, which means that the source is hidden behind dense material, mainly gas and dust, and the X-ray observed have been reflected, but a Compton-thin transmission model could not be ruled out. The equivalent width of the FeKα line is large, indicating too that it is a Compton-thick source. Further observations by Swift Observatory confirmed its Compton-thick nature. The source of activity in the active galactic nuclei is a supermassive black hole (SMBH) lying at the centre of the galaxy. The SMBH at the centre of NGC 4939 is accreting material with a rate of 0.077 M per year. The black hole has been detected in hard X-rays, which are not absorbed by the Compton-thick column, by INTEGRAL.

The galaxy has a large elliptical bulge and maybe a weak bar. It is a grand design spiral galaxy, with two tightly wrapped arms emanating from the bulge. The arms are thin, smooth and well defined and can be traced for nearly one and a half revolutions before fading. Two symmetric arm sections or arcs are observed in the central part of the galaxy. The galaxy is seen with an inclination of 56 degrees. The rotational speed of the galaxy is about 270 km/s. Wikipedia

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NGC 4939 GX VIRGO 10X25 RC8+IMX294.jpg

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NGC 4527 is an intermediate spiral galaxy similar to the Andromeda Galaxy and is located at a distance not well determined, but usually is considered to be an outlying member of the Virgo Cluster of galaxies, being placed within the subcluster known as S Cloud.

Unlike the Andromeda Galaxy, NGC 4527 is also a starburst galaxy, with 2.5 billion solar masses of molecular hydrogen concentrated within its innermost regions. However said starburst is still weak and seems to be on its earliest phases.   Wikipedia

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NGC 4527 GX VIRGO 10X25 RC8+IMX294.jpg

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The galaxy was discovered in 1784 by William Herschel, who described this region as having “a pretty bright star situated exactly north of the centre of an extended milky ray”. Of course the “milky ray” seen by Herschel is actually this spiral galaxy, but with his 17th century observing gear he could only tell that there a fuzzy, blurry structure below the much brighter star.

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NGC 4517 GX VIRGO 10X25 RC8+IMX294.jpg

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NGC 4526 is part of the Virgo cluster of galaxies. Ground-based observations of galaxies in this cluster have revealed that a quarter of these galaxies seem to have rapidly rotating discs of gas at their centres. The most spectacular of these is this galaxy, NGC 4526, whose spinning disc of gas, dust, and stars reaches out uniquely far from its heart, spanning some 7% of the galaxy's entire radius.

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NGC 4526 GX VIRGO 10X25 RC8+IMX294.jpg

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NGC 4665, also catalogued as NGC 4624 and NGC 4664, is a barred lenticular or spiral galaxy located in the constellation Virgo. It is located at a distance of circa 60 million light years from Earth, which, given its apparent dimensions, means that NGC 4665 is about 75,000 light years across. NGC 4665 lies 2 and 3/4 degrees east-south east of Delta Virginis and 50 arcminutes southwest of 35 Virginis. It can be viewed through a telescope at a 23 magnification, forming a pair with an 11th magnitude star 1.5 arcminutes southwest. It is part of the Herschel 400 Catalogue.

It was discovered by William Herschel on February 23, 1784, however, he noted a location 10 arcminutes off the galaxy, where there is no object. It was observed by William Herschel again on April 30, 1786, noting the correct coordinates, and he misidentified it as another nebula. The fact that they are the same object was noted by John Louis Emil Dreyer in 1912 in the corrections of the New General Catalogue. It was also recorded independently on April 9, 1828 by John Herschel.

NGC 4665 has a luminous, slightly elliptical bulge and a prominent bar with high surface brightness. The isophotes appear boxy at the end of the bar. The total bar length is estimated to be near 3 kpc.[9] The bar is slightly twisted, turning near 12 degrees along its axis. Two diffuse, faint arms emerge from each side of the bar and form a pseudoring. The surface brightness of the arms is higher near the bar. The southern arm appears a bit stronger. An arch feature is observed at the east side of the galaxy that could be a partial outer dusty ring. The outer isophotes are elliptical. The total mass of molecular gas is less than 107.3 M.

NGC 4665 belongs to the NGC 4636 group. Other members of the group include NGC 4457, NGC 4586, NGC 4587, NGC 4600, NGC 4636, and NGC 4688. These galaxies, along with NGC 4753, Messier 61 and their groups form the southern boundary of the Virgo cluster. It can be difficult to determine which galaxies belong to which group, especially around the southern edge of the Virgo cluster where there is a confusion of galaxies at different distances. Wikipedia

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NGC 4624 GX VIRGO 10X25 RC8+IMX294.jpg

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NGC 4775 is a 11th magnitude Spiral Galaxy appearing in the constellation Virgo. It is 77 million light years from our solar system.

NGC 4786 is a 11th magnitude Elliptical Galaxy appearing in the constellation Virgo. It is 216 million light years from our solar system.

PGC 43771 is a 15th magnitude Galaxy appearing in the constellation Virgo. It is 323 million light years from our solar system.

PGC 1030299 is a 16th magnitude Galaxy appearing in the constellation Virgo. It is 219 million light years from our solar system.

TSO RC 8" + Risingcam IMX294+ Risingsky software

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NGC 4775+4786  GX VIRGO 10X25 RC8+IMX294.jpg

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