TDA-MMS 2019: Time Domain Astronomy in the Era of Massively Multiplexed Spectroscopy

February 8-10, 2019, Nikko, Japan

This is a by-invitation meeting. The organizers are S. Kulkarni (Special Visiting Professor at Tokyo Tech until March 1; Caltech), N. Suzuki (Kavli IPMU) and N. Kawai (Tokyo Tech, aka "Tokodai"). The workshop is deliberately compact (<30) so as to foster discussion & debate. We note the presence of key people from DESI, KMTNet, SRG, SDSS V and ZTF who are attending the meeting.

There is no registration fee for the invited participants. All overseas visitors are expected to come on their own to Japan. There are two meetings: short meeting at Kavli IPMU (located in Kashiwa) and the main meeting at Nikko (see map below to get a sense of the geography). The local expenses for most overseas visitors and all costs for Japanese participants are paid by a grant from Tokyo Tech (as a part of Kulkarni's appointment), IPMU and discretionary funds provided by SRK.

Please note that the meeting has no secretarial support. Roughly speaking Kulkarni is the SOC, Suzuki (IPMU) is the Japan LOC and Kawai (Tokyo Tech) is the Nikko & lodging LOC.

This is not a standard workshop (with participants preparing slides on the flight). Participants are expected to prepare extensively and ahead of the workshop. This is a meeting in which we mostly undertake organized discussion and debate. No texting nor emailing during the meeting. The goal is to come up with strategies and not tactics. We are close to capacity now. We expect the participants to abide by the Framework document and undertake assigned tasks and reply promptly to emails.

In summary, before proceeding further, please read the following:
Nikko Objectives  |  Participants  |  Short Bios  |  Arrival (Feb 7) & IPMU pre-meeting

IPMU Program  |  Astronomical Facilities  |  Photos at IPMU

Nikko Meeting Program  |  Photos at Nikko   
Fremling Finnish People Talk  |  Sayonara (from the 1966 Bollywood movie, Love In Tokyo)


We are now squarely in the era of time domain astronomy surveys. ASAS-SN has robust coverage of the night sky in both hemispheres and undertakes nightly surveys to 18 mag. ATLAS, though designed for studies of near-earth asteroids (NEOs), is a discovery engine for transients at about 19.5 mag. PS-1 leads the discovery of NEOs. ZTF is undertaking surveys on timescales from minutes to months. ZTF has already found the brightest GW source for the LISA mission, discovered scores of young supernovae and is classifying nearly a hundred SNe per month. We then have specialized facilities motivated initially to attack specific key questions but which are powerful for other purposes also e.g. KMT Net. Finally, Tomo-e Gozen at the Kiso (Schmidt type) telescope has begun the era large field-of-view CMOS imaging.

Meanwhile we are entering the era of highly multiplexed spectroscopy. The first generation of such spectrographs (2dF, SDSS, 6dF) had hundreds of fiber channels. The second generation (LAMOST, Gaia,...) have an order of magnitude larger grasp. DESI will be commissioned next year and SDSS Phase V and PFS shortly thereafter (as well AAT, WHT, ESO, AAT...). A less appreciated development has been the demonstration of ultra-low resolution (R from 100 to 400) spectroscopy for transient classification. This has opened up rapid and robotic spectroscopy on 2-m class telescopes (which are plentiful).

There are other great developments that have just happened (TESS) or about to happen (SRG, "Rosat on steroids"). Kepler mission showed the amazing power of continuously cadenced photometry. TESS is now observing large sections of the sky with continuous cadence. SRG is expected to be launched this year.

These developments naturally raise the question: can we combine time domain surveys with massively multiplexed spectrograph facilities and take advantage of rapid response classification?. For instance, perhaps ZTF with DESI or SDSS Phase V and installing SEDM on half a dozen 2-m class telescopes. Such a triad (focused on shallow surveys so that spectroscopic follow-up will be complete) could lead to classifying many -thousands- of supernovae per year and address fundamental questions (rates, velocity flow in the local Universe) and also serve as a discovery engine. For stellar astronomy, the combination can prove to be truly revolutionary (search for unseen companions).

Big Questions

Some of the big questions that TDAxMMS can answer are listed below.

The Venue of the Main Meeting

The venue of the main meeting is Nikko community hall, Tochigi prefecture. Nikko, located 160 km North of Tokyo, is a famous temple town and synonymous with "bright" and "splendor" (Never say 'kekko' until you've seen Nikko). Nikko is also the hometown of Prof. Nobu Kawai! Participants will be staying at one of two ryokans: Hotel Senhime-monogatari or Hotel Seikoen. The meeting is funded by a grant to Tokyo Institute of Technology, the Kavli IPMU and discretionary funds of SRK.


The main meeting starts at 6 pm on February 8 (Friday), with a welcome reception and dinner and possibly "post-onsen" discussions. The meeting ends at 5 pm on February 10 (Sunday). Prof. Kawai) has arranged for us to stay in traditional Japanese inns ("ryokan") with natural hot springs ("onsen"). Ryokan rules are quite strict. The baths are gender segregated and our Japanese colleagues will educate us about the rules. My wife Hiromi Komiya will be there to help overseas female visitors understand local customs.

The Structure of the Nikko Meeting

The meeting will focus on relatively "bright" astronomy, say <21 mag. This magnitude limit is well suited to current TDA surveys (e.g. ZTF, ASAS-SN) and the followup is easily within reach for SDSSV and DESI (for instance). Perhaps an attractive future meeting could be on a fainter limit (<23 mag) and tuned DES, LSST, DESI and PFS. Participants are expected to contribute and read the following collection of presentations ahead of the meeting.

Homework 1: Facilities

Homework 2: Science & Methodology Goals


Japan is an amazing country in many ways. For instance, you can visit an island populated by friendly bunnies, see smart monkeys sitting in hot natural springs in winter and spend time at relaxing animal cafes (rabbits, cats, owls,...). Or buy a JRPass and get on any train (on time, comfortable, high speed) and watch the countryside go by (whilst connected to internet). Get off at any station, have a meal. If evening then spend the night at a ryokan (replete with hot springs or onsen). Repeat this process for a week!