Puckett Scores, AAVSO Gets the Assist

As most of you know, there are astronomers searching the sky every clear night in an attempt to discover new supernovae in distant galaxies. Some individuals, like Berto Monard and Tom Boles, excel at this, having discovered over 100 supernovae each. One of the more successful supernova search teams is the Puckett Observatory Supernova Search Team, with over 250 supernova discoveries.

All these individuals and teams use robotic telescopes, running scripts that point the telescope and take CCD images of galaxies in a long list of targets they try to cover as often as possible. The nightly images are then “blinked” (rapidly switching between two images of the same star field) by team members looking for the telltale sign of a new star in or near the galaxies in the images. When a team member finds a suspected supernova, this is reported to the IAU, and then listed on the CBAT Transient Objects Confirmation Page. If it is a possible SN it gets a temporary designation of PSN (possible supernova) followed by its coordinates (PSN J01560719+1738468). The search team then asks other astronomers to obtain confirmation images and spectra to confirm the discovery and classify the type of the supernova. 

Once the discovery is confirmed the IAU names the supernova according to their established convention and makes a formal announcement in a CBAT Electronic Telegram (CBET), an IAU electronically distributed notification system. 

Most of the time, the AAVSOnet telescopes only observe supernovae that have been confirmed, are bright at discovery (14th magnitude or brighter), are well situated outside the core of the galaxy (because it makes them easier to measure accurately), and are confirmed Type Ia supernovae, because these are the standard candles professional astronomers are most interested in currently. The AAVSO robotic telescopes are not involved in supernova or nova searches, per se, but in the course of a year we do get several requests to confirm or deny supernovae or novae.

Telescope shelters at Astrokolhoz, the AAVSOnet telescope farm in New Mexico

Recently, Tom Krajci, the AAVSOnet telescope farm operator and technical guru, has been testing the robotic telescope software and hardware to respond to real-time alerts from the Virtual Observatory and other sources.

"It's an obvious need for events like gamma ray bursts, where minutes and seconds count, but even for slower transient events, such as confirming supernovae, it opens doors to new possibilities," said Tom.  "I currently run five AAVSONet scopes on my hill.  The largest scope has an aperture of fourteen inches, and the smallest (Bright Star Monitor) is 60 millimeters.  Now that I'm learning how to customize scripts that filter and respond to VO events, I can tailor the response by choosing the appropriate telescope.  And that's only the beginning."

Tom explained some of the advantages of the current software, "AAVSONet scopes use ACP Scheduler software, which not only is capable of responding to VO event messages, but also creating and sending automated messages back to that community - informing them that we have successfully acquired images of a given event.  This is not just a good news announcement.  It may allow other observers to re-task assets to other targets that have not yet received any follow up observations.  Automation can boost productivity and efficiency in multiple ways that are synergistic."

"I don't want to compete with professionals and amateurs," Tom explained. "I want to augment and complement.  Last week one AAVSONet scope here successfully responded to a GRB alert message and detected the event.  Arne pointed out that many other big telescopes in North and South America also responded to the event, but that there is actually a smaller capability to perform multi-color imaging of these events in the northern hemisphere.  Therefore, I've altered my filter script so that we only respond to GRB alerts north of +20 declination."

But sometimes, even nowadays, in this smartphone, smart telescope, automated world, we have to do things the old fashioned way. Get up in the middle of the night, open the observatory, point the telescope, acquire the data, examine the images and then close everything up when the sun rises.

Saturday evening, January 21, I got an email from Bob Moore, a member of the Puckett Supernova Search team, requesting follow up images of a small galaxy, UGC 9396, aimed at coordinates outside the center of the galaxy. None of the other recipients of the request had much hope due to poor weather at their sites, and I knew it was going to be cloudy in Michigan, so I told Bob I would try to get it in the queue for the AAVSOnet K35 telescope in New Mexico. 

On Sunday the 22nd, I emailed Arne Henden, the AAVSO Director, and Tom Krajci to ask for a TOO (Target Of Opportunity) on the possible supernova. Tom indicated the weather was not looking great, but that he would monitor the situation. Arne’s message to Tom was clear. “If you are going to open, then I'd get a snapshot of this target. If you are planning on staying closed, I wouldn't do anything heroic.”

Just before 4AM EST Monday morning, Tom wrote to say he had opened up two of the telescopes and was going to try to get images of the possible supernova along with some other priority targets as long as the weather held out. 

Tom picks up the story from there. “Before going to bed I reviewed satellite animation loops and it was apparent that the cloudy evening weather would clear off that night, but probably some time after 2AM.

I didn't set an alarm for 2AM, but I woke up anyway and was relieved to see that the clearing trend was happening, although not as fast as I would have liked.  But the winds were not strong, air was dry, and there was no threat of precipitation...which made it 'safe' in my book to open scope shelters.” 

Getting up in the middle of a cold winter night to fire up telescopes and computers to get these images acquired counts as heroic in my book! 

Tom continued, “I only opened two of the seven operational shelters.  The two scopes were K28 and K35, and they had imaging plans for new supernovae that needed confirmation.  I stayed up just long enough to verify that they were running properly with good focus and pointing.  The supernovae would not rise high enough until about 5AM, so I set the alarm for that time.

Checking image results at 5AM, the supernova for K28 had been imaged well, and it was a fairly bright object, not too close to the galaxy's core.  We had good data for the night." But his work for the night wasn't over.

"The target for K35 was a different story.  The object was much fainter and closer to the bright core, and inspection of the B filtered image showed unacceptable E-W smear.  I increased exposure times and submitted the observing plan again, and went back to sleep.  After sunrise I looked at the second set of images, which were better quality and a more appropriate exposure time.” 

I saw his email message early Monday morning and anxiously waited for the image-processing pipeline at AAVSO to kick into gear. By 2:30 that afternoon, I had examined the images, determined a V magnitude and sent off a note to Arne, Tom, Bob, and the supernova discovery team that we had indeed confirmed their discovery. We were the proud parents of a 16th magnitude supernova, and the AAVSO robotic telescope network had acted as midwife in the birth.

SN 2012N in the galaxy UGC 9396

Early Tuesday morning, CBET 2991 landed in my inbox, announcing the discovery of another supernova by the Puckett Observatory Supernova Search Team, SN 2012N. We were happy to see credit given to the AAVSOnet telescope and glad to be part of another modest scientific discovery. Tim Puckett and his team score another supernova, and AAVSO gets the assist.