Photons: gotta catch ’em all

In the beginning of March, we went for an observation at the good and old Pico dos Dias Observatory (OPD), here in Brazil. I think it was the first time I went there during summer, which is the rainy season around these parts, so it’s not actually a good time for observations. We wanted to assess the B&C 0.60 m telescope in its potential to do followup observations for KELT (Kilodegree Extremely Little Telescope – pretty funny name: a bit of a satire on ESO’s “very large” telescopes, I imagine), which surveys the sky looking for hot Jupiters around bright stars. So yeah, we went there to hunt some exoplanets.

To do that, we used differential photometry, a method that compares how the brightness of different stars in a given field of view vary with time. In our case, we wanted to see how the brightness of the exoplanet-host dipped when a transit occurred. To do that, we need as many photons as possible to fall on our detectors, so we can have measure the dip with a bigger certainty. Results were very interesting, and I will write a more complete blog entry about our observations in the near future. But, while we were there trying to catch the light (or rather, the shadow) of exoplanets, I was, as always, trying my hand on some night sky pictures.

While I left the telescope doing a very long series of exposures, I set out taking my camera and tripod to do some imaging. And during one of my first trials, I was lucky enough to have a really bright meteor cross the sky and go over the 1.60 m telescope, and even more lucky to have my camera exposing at the time. And further lucky to have set a high ISO, so the meteor stood out beautifully in the picture. Unfortunately, since it was one of the first pictures, the camera wasn’t focused very well (in fact, it was pretty terrible), so it didn’t end up as good as it could be. Also, the Moon was 88% illuminated, so we get this effect of “daylight with stars” in long exposures (in all pictures, click to embiggen).

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A bright meteor over the 1.60 m telescope, Mar 02, 2015, UTC 03h42. It was the first time in my life I got a meteor on picture.

However, things weren’t that bad, because the sky went completely dark after around 4 AM, when the Moon set, so there was this short window of darkness until the twilight, and I was eager to take advantage of it. I haven’t had many chances of taking pictures in really dark places with really dark conditions before, so this was a good opportunity.With the help of some bright stars, I managed to focus the camera and I took these two following pictures. The first one was taken using ISO 3200 and, luckily enough, I got another meteor (a dimmer one, though) and a satellite! The second one was taken with ISO 1600, which has less noise, but it is less sensitive, and so I had to take more exposures, resulting in longer star trails (I don’t have an equatorial tracking tripod). As you can imagine, we have to work with a trade-off between more light and noise/trails.

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The Milky Way bulge, a meteor and a satellite. 15×10 s of exposure, ISO 3200, F3.5. The light pollution comes from the cities around the Mantiqueira Mountain Range.
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The Milky Way bulge, no meteor and no satellite on this one, plus star trails. 20×10 s of exposure, ISO 1600, F3.5.

Here are two other shots taken aiming towards the domes of the observatory, and they are probably my favorite ones. Not only because they look fairly good, but because it was actually very fun to take these shots. The site was so dark, that it was hard to find my way around the observatory until my eyes didn’t get used to the darkness (it took about 10 minutes). Once your pupils are fully open, we can see so many stars in the sky that it is difficult to find the asterisms of the constellations.

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The Milky Way bulge over the dome of the 1.60 m telescope at Pico dos Dias Observatory.
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The southern band of the Milky Way is very rich. In this picture, you can find the Coalsack Nebula, the Eta Carinae nebula and various star clusters.

I think those were very productive nights. We obtained good results from the observations, I got a chance to take pictures in really dark conditions, and food was good. The food from OPD is never a let down. Word is that, when the weather is bad, astronomers like to spend their time lounging at the 1.60 m telescope pantry. Luckily we didn’t need to do that.

 

 

Photons: gotta catch ’em all

Dipping my feet

During the past weeks, I’ve been trying some astrophotography at my place. Not for the first time, because I have done it (not very successfully) before, but now a friend of mine (who is also into astronomy and photography) lent me this cool camera support for backyard telescopes. Although it is designed to work better with smaller cameras and cellphones, I can attach my Nikon DSLR into it by taking out the lenses and using it in the primary focus. So this is the good news. The bad news is: well, if you ever tried astrophotography, you will know better than anyone how frustrating and painful it can be at first.

Astrophotography is difficult. It is probably one of the biggest challenges I had in my life, one that I could not perform well yet. It’s not like you just stick a camera into a telescope, press a button and a beautiful picture magically comes out ready to be published and admired. There are many, many steps to do before you get something worth showing. In regular photography, I would say that your performance depends a lot on your mood, on how well you can frame and capture an image, on the ability to work your way around lighting, how well you know your own camera and even on your luck. Astrophotography, on the other hand, has so many technicalities and small details, that it can drive one person crazy. It’s not just a question of practice, because you’ll be seriously limited by your gear. For instance, it’s not every telescope that can take good planetary images, and it’s not every camera that can be controlled by a computer (I’m looking at you, Nikon). These are the bad news. But I know I shouldn’t expect much, since all my gear is among the lowest end available, but I guess it’s a good place to start, right? Another issue that I have not mentioned yet is that astrophotography is expensive, especially if you intend to buy things in Brazil. Just so you can have an idea, a telescope that costs US$ 100 in the US costs 4 times much here.

So, here are the main problems I am having, in order of importance:

  • Terrible telescope mount: probably the worst issue, because even my own steps around the scope can shake the exposure and create smudges and star trails. Also, aligning the scope with the south pole is a HUGE pain in the ass
  • Light pollution: very problematic too, mainly due to the large number of light poles around my house (I live in one of the main streets of the neighborhood)
  • Lack of software support for Nikon DSLR: seriously, if I knew that there was no software that could fully control a Nikon DSLR, I would have bought a Canon. I wish I had researched this better before I made the purchase

Notice: if you know a way to work around these issues (mainly the lack of software support for Nikon DSLR), please let me know in the comments or through an email!

But enough of the frustration and rant. I thought I would talk about it first so I would have an excuse for my pictures, which are not… that good… I mean, it’s not wallpaper quality but, hey: baby steps. One day I will have a good scope and live in a place with less light pollution. Until then, I will keep practicing. Another option that I want to try is to make movies with my camera and stack the frames using Registax. In fact, I have tried that with the Moon, but I could not get Registax to work well. I guess I need to learn how to use it beyond just clicking a few buttons. Anyway, here you go (click them for a 1080 px version, even though I don’t recommend for some of them):

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Testing the magnification of my gear
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The Ptolemy Cluster, located near the tail of the Scorpion. The red stains are due to light pollution invading the exposure. Exp. time: 5 s; ISO 3200; prime focus; processed on GIMP.
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Another shot of the Ptolemy Cluster. Exp. time: 4 s; ISO 3200; prime focus; processed on GIMP.
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The Moon on September 4th. Exp. time: 1/60 s; ISO 200; prime focus; unprocessed.

And here is my favorite picture of them all. For this one I didn’t actually use the telescope, just the camera on my standard tripod. But it turned out to be cool, even though the light pollution hurt a lot of it.

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The galactic bulge of the Milky Way. It is located towards the constellation of Sagittarius, which hangs out overhead here at the southern hemisphere during winter. Exp. time: 15 s; ISO 3200; focal length: 18 mm; no tracking; processed on GIMP.

If you’re interested, this is my gear (as I said, these are very low end stuff for astrophotography):

  • Telescope: Celestron PowerSeeker 127EQ
  • Nikon D3100
  • Camera tripod Hama Traveler Compact Pro
  • Camera telescope support that I don’t know the brand (see picture)
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Camera-telescope support that I’ve been using
Dipping my feet