Salvatore Iovene / Mostly astrophotography and code

I’m just looking at my git-log, and I’m dumbfounded to realize that I’ve been hard at work on the latest and greatest AstroBin update for six weeks.

I must have had a wonderfully good time, because these weeks of late night working to improve AstroBin have really been flying.

Looking at the difference between the current master branch and my 1.10 development branch is even more astounding:

 434 files changed, 69324 insertions(+), 71068 deletions(-)

Now, not all these insertions and deletions are actually my code, of course: I’ve upgraded several large JavaScript libraries, for instance, and that’s a lot of pluses and minuses. If you look closely, you will see that the net amount of lines of code has actually gone down. That’s fantastic because I’ve added a lot of new features, and there were plenty new auto-generated files, like database schema and data migrations, and they can be large.

Overall, this new version of AstroBin is the largest incremental change I’ve had since launch! So let’s see what’s new.

Visible improvements

5-star rating system replaced by “Like” button

Many of you have seen this coming. There have been many discussions all over the place. In the end I’ve decided that a 5* rating system is just not ideal for astronomical images. Nobody needs “negative” votes like a 1 and a 2. I’ve implemented a Like button to replace the 5 stars. Old votes of 4 and 5 will be converted to a Like.

Because of this, a Favorite (heart) button doesn’t make sense anymore, so I’ve renamed it with “Bookmark”, and it works the same way.

New activity streams with more detail

The activity stream has become the central part of the front page experience. The activities are more detailed (for instance with the content of the comment, for comment actions) and thumbnails. It’s gonna be better to see what’s happening on AstroBin! Furthermore, there is a global stream with all activities, and a personal stream with activities from people you follow, and on their images.

Easier way to manage people you follow

A lot of focus has been placed on the follower/followee interactions. You get to see your follower numbers, and a list of people you follow / who follow you.

Smart thumbnail

AstroBin will try to find the most interesting area of the image, to generate the thumbnail. So if you have a picture with the moon in a corner, and the sky completely black, AstroBin should be able to generate a small thumbnail that has the moon in it, and not just a black square!

Revisions are solved too

This one has been in my todo-list for a while… now Revisions are first class citizens too! The will get plate-solved independently from the main image upload :)

Sky plot

Solved images have a small star chart next to them! How cool is that?

Behind the scenes

Complete refactoring of thumbnail generation

Instead of generating thumbnails by manually running PIL code after each upload, I’ve taken Django east-thumbnails into use. This allows me to generate whatever thumbnail size on the fly upon request.

This change simplified a lot of AstroBin’s code, and unifies the displaying of images everywhere, be them small thumbnails or full size ones.

Such unification allows me to cache the entirety of an image’s HMTL code, for faster performance and less strain on AstroBin’s database server.

In addition, generating thumbnails only when they are needed will help me lower the hosting costs. We are approaching half a terabyte.

Finally, I was able to completely remove the use of celery for the processing of images: they’re not run in the background anymore, but, as I was saying, they are now being generated on the fly.

For the reason that thumbnails generated for the first time won’t be cached, nor will they actually exist as physical files, displaying of all images on AstroBin now happens asynchronously.

Complete refactoring of uploads processing

Handling uploaded images was pretty much the first thing I did when I started AstroBin back in 2010 (has it been already three years?!?) and I wasn’t very experienced with web development back then, so it’s obvious that I made some mistakes.

One of them was not taking advantage of Django’s ImageField and the wonderful django-storages, by pretty much doing everything manually with boto. Now, that part is done properly and a result is much leaner and more robust.

Much faster, always blind, plate-solving

Pate-solving won’t happen on AstroBin’s server anymore, but using the API provided by nova.astrometry.net. This means that AstroBin’s server will suffer less strain, and be faster overall. Astrometry.net have a massive server, so plate-solving will be super fast! Usually 10-60 seconds, in my experience, for reasonably solver-friendly images. The plate-solving happens on the fly the first time a deep-sky image is displayed by a user and you get real time status updates.

Those were the main features. There have been other smaller improvements and bug fixes, plus some care for the IE and mobile browsers. I’m really excited about this new release of AstroBin and I hope it will strengthen the community and make the users even happier!

During some moonless hours, this August, I aimed my telescope to NGC 7129, a beautiful reflection nebula in Cepheus.

Young suns still lie within dusty NGC 7129, some 3,000 light-years away toward the royal constellation Cepheus. While these stars are at a relatively tender age, only a few million years old, it is likely that our own Sun formed in a similar stellar nursery some five billion years ago. Most noticeable in the sharp image are the lovely bluish dust clouds that reflect the youthful starlight. But the compact, deep red crescent shapes are also markers of energetic, young stellar objects. Known as Herbig-Haro objects, their shape and color is characteristic of glowing hydrogen gas shocked by jets streaming away from newborn stars. Paler, extended filaments of reddish emission mingling with the bluish clouds are caused by dust grains effectively converting the invisible ultraviolet starlight to visible red light through photoluminesence. Ultimately the natal gas and dust in the region will be dispersed, the stars drifting apart as the loose cluster orbits the center of the Galaxy. (APOD)

I collected 14.8 hours in LRGB over the course of five nights.

The image can be seen on AstroBin as well.

This new moon I decided to try a galaxy. NGC 6503 is not a commonly imaged target: there are only seven instances on AstroBin.

It’s a dwarf spiral galaxy located in the Local Void, 17 million light-years away in the constellation of Draco.

The Local Void is a vast, empty region of space, lying adjacent to our own Local Group. Discovered by Brent Tully and Rick Fisher in 1987, the Local Void is now known to be composed of three separate sectors, separated by bridges of “wispy filaments”. The precise extent of the void is unknown, but it is at least 150 million light years across and may have a long dimension of up to 70 Mpc (230 million light years). The Local Void also appears to have significantly fewer galaxies than expected from standard cosmology. (Wikipedia)

For this image, I let my equipment run for ten hours and twenty minutes.

The image can be seen on AstroBin as well.

This time, taking advantage of the New Moon nights, I went for a relatively easy and widely popular target: the Bubble Nebula, NGC 7635.

Here’s a quote from Wikipedia:

NGC 7635, also called the Bubble Nebula, Sharpless 162, or Caldwell 11, is a H II region emission nebula in the constellation Cassiopeia. It lies close to the direction of the open cluster Messier 52. The “bubble” is created by the stellar wind from a massive hot, 8.7 magnitude young central star, the 15 ± 5 M☉ SAO 20575 (BD+60 2522). The nebula is near a giant molecular cloud which contains the expansion of the bubble nebula while itself being excited by the hot central star, causing it to glow. It was discovered in 1787 by William Herschel. The star SAO 20575 or BD+602522 is thought to have a mass of 10-40 Solar masses.

And this is what APOD has to say about it:

Blown by the wind from a massive star, this interstellar apparition has a surprisingly familiar shape. Cataloged as NGC 7635, it is also known simply as The Bubble Nebula. Although it looks delicate, the 10 light-year diameter bubble offers evidence of violent processes at work. Above and right of the Bubble’s center is a hot, O star, several hundred thousand times more luminous and around 45 times more massive than the Sun. A fierce stellar wind and intense radiation from that star has blasted out the structure of glowing gas against denser material in a surrounding molecular cloud. The intriguing Bubble Nebula lies a mere 11,000 light-years away toward the boastful constellation Cassiopeia.

For my interpretation, I used L, Hα, and RGB filters, for a total integration time of 19 hours.

The image can be seen on AstroBin as well.

Here’s my latest astrophotography work, the beautiful reflection nebula NGC 6914, in Cygnus.

Dipped in a sea of red, this blue haven is thusly described by the folks at APOD:

The complex of nebulae lies some 6,000 light-years away, toward the high-flying northern constellation Cygnus and the plane of our Milky Way Galaxy. With foreground dust clouds in silhouette, both reddish hydrogen emission nebulae and dusty blue reflection nebulae fill the 1/2 degree wide field. [..] Ultraviolet radiation from the massive, hot, young stars of the extensive Cygnus OB2 association ionize the region’s atomic hydrogen gas, producing the characteristic red glow as protons and electrons recombine. Embedded Cygnus OB2 stars also provide the blue starlight strongly reflected by the dusty clouds.

My rendition took a lot of integration time, possibly more than it was, necessary, but the result is very nice and noise free.

I ended up totalling a whopping 67 hours, 41 of which in Hα. The Hα subs were all collected when the Moon was up though, but they didn’t seem to suffer terribly from it.

The equipment used was the usual: GSO RC8 with APCCDT67, Moravian Instruments G2-1600FW, Astronomik LRGB and Hα 6nm filters, and a 10Micron GM2000 mount.

The image can be seen on AstroBin as well.

It’s unusual for me, as of late, to publish images with integration times that are less than biblical, however this time I thought I might content after one night only.

The image above depicts B143, that is the 142nd object of the Barnard catalog, a dark nebula in the constellation of Aquila.

Two thousand light-years away, this a cloud of dust that is not being ignited by any stars, therefore appearing as a black void against the tapestry of stars of the Milky Way.

The image was acquired during the course of five hours, with a classic LRGB composition. You can view it on AstroBin as well.

In the past week I’ve worked on collecting data on some dark nebulae in Cepheus: B161/162/163 and others.

My setup now has an AstroPhysics CCD67 focal reducer in the optical train, which means I’m working at a focal length of about 1225 mm, and a focal ratio of about f/5.54. The telescope was also collimated better, and I only have a slight residual tilt, almost invisible.

This image is a simple LRGB composition, in a 2-panel mosaic with a total integration time of 17 hours.

Please note: no noise reduction was applied!

The dark nebulae appear in a vast field of red hydrogen emissions, which is known as the IC1396 complex.

The image can be seen on AstroBin as well.

With the recent great weather (I haven’t seen a cloud in weeks!), I was able to work on a deep rendition of the famous Elephant Trunk Nebula, aka vdB142.

This is a collaboration with my friend Samuel Díaz López, who collected the O[III] data.

With a GSO RC8 and a Moravian G2-1600, I collected 36x1800” Hα frames and 36x1800” S[II] frames. With a GSO RC10 and an Atik 4000, Samuel collected 30x1800” O[III] frames.

The grand total is 102x1800” frames, which is 51 hours.

The clarity of the signal and the resulting ease of processing, plus the depth of the image, which shows a lot of really faint wisps of matter, makes the time spent really worth it.

It took about three hours to process the data. As usual, I composited a “Modified Hubble Palette”, with the following properties:

Red: 50% Hα + 50% S[II] Green: 85% O[III] + 15% Hα Blue: O[III]

The stars were treated separately, with their color coming from a bicolor composition of the Hα and O[III] data.

The nebulosity was treated using Jukka Pekka Metsävainiö’s tone mapping technique, obviously adapted to PixInsight.

After an uncountable number of late nights and many a moment of abysmal dismay, and with many things still not working properly, I can finally present the first image in nine months whose luminance was entirely acquired by me, and that finds my content.

I worked for a few nights on NGC 5906/7 (there’s ambiguity in the naming), collecting 51x600” luminance shots with a GSO RC8 at full focal length.

Unfortunately there isn’t the faintest hint of the feeble tidal streams visible in Gabany’s image.

The color data was kindly provided by Samuel Diaz Lopez.

Also available on AstroBin

After the recent breakthrough, and thanks to some precious help by Giancarlo Calzetta, I was finally able to tame the bulk of the problem.

What’s left is some differential flexure, at least when imaging west. In the meantime, I was able to produce this quick jab at M13 (thanks Samuel for the RGB data!)

The image could be better focused (I messed with the focuser when I was in Nerpio, but it’s fine now) and the RGB data is not calibrated, so if you zoom in you can see lots of colored hot pixels. I’m still happy I can see the end of the tunnel.