Tuesday, June 7, 2016

Trio of Interacting Galaxies in Virgo

A trio of interacting galaxies in Virgo about 90 million light years away. This trio is also included in Halton's Atlas of Peculiar galaxies as entry ARP286. NGC5566 is the largest galaxy of the 3 at almost 150,000 light years across. NGC5560 has been stretched by the interaction with 5566.


Wednesday, February 17, 2016

NGC4449 Galaxy in Canes Venatici


NGC4449 is a very unique object. It is a irregular galaxy ~12Mly distant in the constellation Canes Venatici. It is part of the M94 group.

Its shape is attributed to interactions with nearby galaxies. It has many star clusters and is believed to have a very high rate of star formation.

It exhibits excellent detail and seems to have a central bar structure with many filaments growing outwards.

The Hubble picture (inset) shows the incredible amount of star formation in exquisite detail.



Sunday, February 14, 2016

The Coma and Leo Galaxy Clusters

The Coma and Leo Clusters of Galaxies (Abell 1656, 1367)

This region of the sky is extremely rich in galaxies. The coma cluster along with the Leo cluster (abell 1367) of galaxies form part of the Coma supercluster.

At the center of the cluster are the two bright supergaint elliptical galaxies N4889 (also NGC4884) and N4874.

N4889 is ~300 Mly away and N4874 is~350 Mly

The smaller galaxy just north of NGC4889 in the image is N4882 and is ~310 Mly.







Friday, February 5, 2016

Mag 21.7 Quasar in Virgo

Decided to go Quasar hunting. Conditions were very good this evening (or rather as good as it gets here... NELM 4 -4.25 at zenith), low humidity

Managed to get down to mag 21.7 using short exposures 10x25s (average stack) using the Ultrastar mono x2 binned. This was using the C8 at F5. No LP filter.

The NGC4666 (Superwind field is littered with Quasars). I identified and marked 3 but there are more in the image.

The most distant one in the image that I marked is barely visible and required an aggressive stretch. It has a magnitude of 21.7 and a redshift of 2.25 which means light from that quasar has been traveling for ~11.6 billion light years. If you take into account the expansion of space time the distance today would be ~19 billion light years. Pretty much incomprehensible scale.

The mag 21.7 quasar is at the limit of detection using this sensor and short exposures. The pixel size makes a big difference in the ability to go deep. With x2 bin the Ultrastar Mono has large 13 micron pixels which are able to capture very faint electromagnetic flux.



Monday, February 1, 2016

Review of the Atik Infinity Color Video Astronomy Camera

Atik Infinity color camera initial impressions

I have had the opportunity to play around with this camera for a few days. In my view with the Infinity Atik is trying to establish a new product segment which addresses a very real gap/need in the market. I choose to call it “Casual Astrophotography”. There are many of us who want a near real time imaging experience at the scope without sacrificing resolution/quality too much and/or dislike post processing.


Having done serious and casual imaging for many years I don’t think this camera will replace the high end cooled AP CCDs anytime soon for a number of reasons although there will be some cannibalization as there is a sub segment which prefers more instant results. My guess is that Atik did the math and they realized that the expansion of the user base from this product will more than make up for that (I think it will).

This product also addresses a portion of the Electronically Assisted Observing ("EAO") segment. The color version of the Atik Infinity camera is relatively slow with regards to acquisition speed compared to other EAA solutions out there but does produce images more closer to long exposure imaging. In my view to fully leverage this camera for EAO you need a very fast optical setup running at around F2 like a hyperstar or a RASA.

In summary, I think the Infinity is the first integrated seamless casual imaging user experience which addresses both the inexperienced user as well as an experienced imager looking for a more real time experience. The little details make a big difference and that is very true for the Infinity. Atik has really thought through the design and the hardware and software together deliver a very seamless experience. The software is very stable and the performance is excellent.


The positives and development needs

The Positives
  • I have to start with the fact that there is one single tab for the application and the user interface focuses on only the most essential controls. This is great for the less experienced user.
  • There are also auto settings for most adjustments which again makes the learning curve much smoother for newcomers.
  • But the feature I love the most is that I don’t need to take dark frames (and also that I don't need cooling to achieve that - I have used cooled CCDs in the past and they come with their own issues). I just start viewing/imaging right away and find that the freedom to change sub exposure time as required changes the user experience completely. It does truly feel like a “video astronomy” experience rather than an imaging experience.
  • The stacking is incredibly fast… almost instantaneous. The software is fast enough to stack 1s subframes in real time even in slightly busy star fields. I have not had a chance to try it out but I know that the just released Starlight Live v2.0 also has significant performance improvements so that gap should be less now.
  • The ‘Image Quality’ section continuously displays the FWHM of the image. I find this more useful than I thought I would. While stacking I can see the variance in seeing/tracking for various exposures and gives me insight into what is going on with the exposures. Also combined with a Bhatinov mask makes focus very accurate.
  • For all the above reasons this is an excellent camera for broadcasting. Minimum fiddling required and a truly integrated experience really help with ease of use. If you are doing broadcasting, are ok with 30-60s sub exposures I think this camera will fit the bill nicely. Although there is no compatibility with NSN yet.
  • The other thing I really like is the physical design. As my primary EAA setup is an Alt Az Evolution mount, the flat design of the camera makes it easier to clear the base (although I managed to clear the base with the Ultrastar Mono as well using T Threads at f3.3 but with only 3mm to spare!)
  • The camera also has T threads which make attaching to my optical chain and achieving the correct spacing much easier.

Room for improvement - I present these more as constructive criticism for a very nascent but excellent product and not as negatives.
  • Achieving color balance has proven to be a little challenging. The images appear “yellowish green’ even after using a LP filter. I live in a red zone and the camera is practically unusable without a LP filter (which is true for other color cameras as well). The v1.2 beta of the Infinity SW allows for manual color balance but the controls are not intuitive for someone new to Astro-photography. Even to me the terms offset and stretch for a color channel (while very straightforward in what they do) did not mean much until I was able to conceptually relate them to what I do in post processing.
  • You cannot specify the stacking approach. In Starlight Live I am able to specify the stacking method which is useful. For example when imaging galaxies or galaxy clusters on days with very bad skyglow I resort to very short exposure stacks 5-10s with my mono camera (no LP filter as it kills a large part of the signal from galaxies) and then sum them for maximum SNR. The results if the seeing and transparency are good rival my dark site results. Less of an issue for the color camera but something that would be very useful for the mono camera.
  • Information overlay (or lack of) when saving Images. Again this is a feature I like a lot in Starlight live which is the automatic labeling of images when you save with information like target name, exposure time, time and date. This is a simple fix but one which makes sharing a lot easier. Taking screenshots is not my preferred way for sharing captures.
  • The FWHM displayed for the image gets thrown off by bright galaxy cores e.g. for M31 it displays a FWHM of 100+ for a 30s exposure vs. 2-4 for an image of a starfield! This makes comparison harder to the previous object to ensure there is no degradation in focus. Also the number means less to the user overall. This is not a complicated fix (use a Gaussian filter and ignore outliers) but needs to be resolved.
Other
  • Very slow for EAO. Would recommend running at F2 using a Hyperstar or RASA setup.
  • While it seems to me that the camera's custom circuitry is potentially manipulating gain to improve SNR the image acquisition is still slower vs. the other cameras EAA users are used to. My estimate is that it needs at least 2x the total exposure time of the ASI224 and LS X2C (This will more or less hold for the Ultrastar C as well). Also the image quality and subtle detail produced by the ASI224 is better (of course requires more effort and fiddling and I think this is exactly where the Infinity and Starlight Live (if you chose the Ultrastar C) user experience differentiate themselves).
  • Due to the higher read noise (still low compared to some other imaging CCDs) some objects will respond well to shorter exposures and some will require longer exposures. I would say 30s should be the baseline and you can vary it up or down from there as required (again this should hold true for the Ultrastar C as well). I will post some comparisons of the same object at different sub exposure times.
  • The Infinity needs a separate 12V/1A power supply. The Ultrastar cameras are powered via USB and use a frugal 200mA

All images with Nexstar Evolution 8 @ f3.7, Orion LP filter and Atik Infinity taken from a white/red light pollution zone.

M31 & M33. Both were at the Zenith when imaged.

M31 1x30s (some field rotation is present as it was the the zenith and I was using my Evo 8.


M31 13x15s (shorter exposure stack)


 The Bubble 5x60s


Horsehead 6x60s


NGC 891 5x60s


M33 6x60s
 

The following images were taken with a AT72ED 72mm at f4.5 with a Focal reducer/flattener, Orion LP filter, Evolution Alt Az mount and the Atik Infinity color from a white/red LP zone.

These images are longer total exposures (not typical of EAO) and are examples of casual astrophotography.

Rosette 12x90s
  

NGC7000 North America Nebula 11x60s


Horsehead and Flame 12x60s


M31 Andromeda Galaxy 14x60s


Sunday, January 31, 2016

M87 relativistic jet

M87 relativistic jet. Exposure time: 4x25s using the Ultrastar mono and a Evolution C8 @ F5

Jet of plasma being ejected by a massive black hole consuming matter. It is also one of the strongest radio sources in the sky. It extends about ~5 thousand light years from the center of M87 (which is one of the most massive elliptical  galaxies known to us. The full extent of the jet can be seen in Hubble pictures.

The challenge in capturing this jet is not to overexpose the galaxy. Hence the jet is actually better captured in very short exposures. Observing conditions are also very important. While the light pollution at my location was unchanged this evening presented relatively good seeing conditions.




More here: https://en.wikipedia...wiki/Messier_87

See this Hubble video as it zooms in on the jet (composite of images taken over 13 years to show how the jet changes): https://www.spacetelescope.org/videos/opo1332a/


Hubble image of the jet:

Credit: NASA and The Hubble Heritage Team (STScI/AURA)