I found this online today, and thought I’d share. The engineers for Hyper Suprime-Cam on the Subaru Telescope put together a video of the Subaru dome opening during twilight, You can find the original video here on a blog about the commissioning of Hyper Suprime-Cam, Subaru’s newest wide-field camera (Note: the blog is in written in Japanese).
When you’re observing you don’t often get this view as sunset is one of the busiest times when you’re an astronomer getting ready for the start of your night (likely of one or a handful that semester) on the telescope. The data you currently review on Comet Hunters is the public archival data from Subaru’s Suprime-Cam. Each of those nights when the weather was good, something like below happened as the observatory prepared to start the nightly calibrations.
Video credit: Yousuke Utsumi
The science team is working on incorporating data from the Hyper Suprime-Cam (HSC) survey into Comet Hunters. We started with the archival Suprime-Cam data first to get a better understanding of what are the false positives and challenges for identifying Main-Belt Comets (MBCs) in data from 8-10-m class telescopes. We’ll continue with both datasets as there’s more Suprime-Cam asteroids, but when we have the chance we’ll move to reviewing the new HSC observations hopefully a few days after they’re taken.Most previous asteroid detection surveys are using 1-3-m class telescopes, so there are bound to be surprises that we wanted to know about before we developed the decision tree for the HSC snapshots on to the site. So we launched Comet Hunters with the archival Suprime-Cam images first. Now that things are going smoothly, we can turn our attention to the HSC data.
We combined your classifications from the first batch of Suprime-Cam images and had 125 candidates in need of further vetting. Thanks to volunteer Tadeáš Cernohous who on Talk went through our list comparing repeat images of the asteroid at slightly different positions in the same batch of subjects. What we learned that all of the candidates are unfortunately blends with stationary background sources. There are lots of faint background blobs that the asteroid moves on top of overlapping in the images creating very tail-like features. All of these images the science team would have had said has a tail.
A few examples are below (all blends with faint background sources):
There’s a lot more blends than we had anticipated given some of the team’s past experience with 2-m asteroid survey data. It’s still very much worth digging into the rest of the Suprime-Cam archive to look for MBCs. There might be many blends, but there could still be undiscovered MBCs too! Knowing that the background blends rate is much higher because of the increase in the photon collecting bucket is extremely useful. From the candidates, we could see the blends are faint blobby structures that would be likely hard to get a source extractor to pick up in all cases. Because of the quality of the HSC data and the repeat observation cadence we can try and take this into account possibly by checking the image of the asteroid and the repeat image of the same position take later on in the same night (not all Suprime-Cam images will have that and are taken in all types of sky conditions).
Now the Comet Hunters team is thinking about how best to develop a classification interface for the HSC data to include this. In the meantime, there are new Suprime-Cam images in need of review at http://www.comethunters.org if you have a minute or two to spare.
Thanks to everyone who has helped out with Comet Hunters so far. As noted in a previous blog post, with your help, we’ve completed the first batch of images from launch and have compiled a preliminary list of potential comet candidates based on your classifications, and are currently in the process of vetting those candidates.
We are pleased to announce that new data is now available! We’ve fixed some issues with our data processing software (in particular, a bug that led to a large number of off-center asteroids that many of you noticed), and so this new set should be easier to analyze and classify. With the newly uploaded batch of brand-new images as well as some re-processed images that we’ve shown before, we hope to identify many more main-belt comet candidates with your help. Good luck and happy hunting!