Time Domain Astronomy

UTRGV Time Domain

Astronomy Group

On the left myself, Mario Diaz at the center of the group.

On the right from top starting at the left and row by row: Tania Peñuela (postdoc), Martin Beroiz (PhD student), Shuang Liang (MS student), Juan Garcia (MS student), Americo Hinojosa Lee (MS student) , Ervin Vilchis (MS student), Lorena Lozano (Veterans Memorial Early College High School physics teacher) and undergraduate physics majors  Andrea Hinojosa Lee, Alejandro Hinojosa Lee, Wahltyn Raythn, and Daniela Rojas, engineering  major Jose Puente (Nompuewenu astronomical observatory official engineer), and Texas Southern University REU student Ryan Woods.

What is Time Domain Astronomy?

It is the study of the change over time of objects in the sky. Which objects? There are many: in ancient times at the beginning of the History of Civilization when humankind was observing the regularities in the sky that could help to find the most appropriate times for the sowing and harvest seasons or for when the rains should be expected, perceived it as very quiet and calm.  Except for a few of these objects that weren’t moving like all the other stars: these were the planets. But for the most part the sky was quiet and serene. When something very rare like a comet was appearing in the sky it was thought as something so rare and extraordinary that many people saw them as purveyors of bad luck. That’s the origin of the term disaster which in latin meant “bad star”.

But history has records that civilizations have observed and registered events in which very bright objects appear in the sky to eventually dim after a few days.

Chinese astronomers recorded in 1054 a star bright enough to be observed in daylight: we know now that this is the remnant of a supernova explosion: the so called Crab nebula (https://en.wikipedia.org/wiki/Crab_Nebula ).

With modern tools and particularly since the last century we discovered that the sky is not so quiet and that many stars change their brightness and also, particularly in the last few decades that there are many explosions, some of them extremely powerful, which happen in the universe, that many stars and astrophysical objects change their brightness, and consequently their outpour of energy, some times quite dramatically.

It  is hence interesting and necessary to move away from the one time long exposure of photographic plates that were registering one instance in the life of an object and have instead a series of quick and fast snapshots that can show the evolution with time of these objects. More than photographs, we need movies. The obtention and study of many snapshots of an object that would let us study its evolution and change  with time is  then called time domain astronomy.

A successful example of time domain astronomy is the study of a particular type of star explosions that appears very bright in the night sky: supernovae (for example SN1987A was visible at night with the naked eye when a star exploded in the Magellanic clouds, our closest galactic neighbor. After many careful follow-up studies core-collapse star explosions have been tied clearly to a bursts of gamma radiation (GRB) which last longer than a couple of seconds. For many years the origin of GRBs detected by NASA satellites like Swift and Fermi where quite mysterious: time domain astronomy has contributed to solving it and to present a better integrated picture of the demise of certain stars at the end of their life cycle.

Our group is interested in observing a particular kind of explosions that are expected to be the source of very powerful emission of gravitational waves (see Einstein’s unfinished Symphony ): the merger of two neutron stars after dancing ever closer around their common center of mass for several hundred million years. The continuous emission of gravitational waves makes the system loose gravitational energy and the ever falling of one into the field of the other makes it loose its stability and a plunge becomes unavoidable. When that happens one of the stars, which are extremely compact and dense, get disrupted and the in-falling mass of one of them into the other produces a very bright explosion that would peak in the infrared and also although somehow dimmer in the visible portion of the spectrum. GRBs of very short duration (less than two seconds) are produced and the whole explosion would fade away quite rapidly. The optical glow of this event has been dubbed a kilonova (not quite as bright as a supernova but still brighter than a nova explosion -a cataclysmic explosion of a white dwarf star engulfing a binary companion-).

Our group is a member of a collaboration created to search for kilonovae associated to the merger of neutron stars: the Transient Optical Robotic Observatory of the South (TOROS). This link describes the goals and mission of TOROS: The TOROS Project


Reading materials for our group members and anyone interested in studying the subject:


A very elementary introduction to gravitational waves can be followed at this link:

Einstein’s unfinished symphony

The following preprint http://arxiv.org/abs/1209.0667  discusses sources detection and searches in some more detail.

This article http://spectrum.ieee.org/computing/hardware/waiting-for-gravity  was published In the Institute of Electrical and Electronics Engineers (IEEE) Spectrum magazine.

Gravitational Waves: New Observatories for New Astronomy (The Physics Teacher, October 2006)

Sounding Out the Big Bang (Physics World, June 2007) -

See more at: http://www.ligo.org/students_teachers_public/read.php#sthash.9apVVS0f.dpuf

A more advanced and rather technical introduction to gravitational radiation can be followed here from one of my lectures in the Introduction to General Relativity class:



This material consists in slides I typically use for an introductory class in Astronomy (a class from the general education core):


The following are very concise introductions to the life and death of stars:

A wikipedia definition of stellar evolution: https://en.wikipedia.org/wiki/Stellar_evolution.

The INTERNET Stellar database has a page on stellar evolution:


The following is a NASA webpage on stellar evolution:


Arthur Holland and Mark Williams, from the Univ.. of Michigan webpage on stellar evolution: http://www.umich.edu/~gs265/star.htm

The electronic universe project: http://zebu.uoregon.edu has some useful material for astronomy in general http://zebu.uoregon.edu/galaxy.html  and on stellar evolution: http://zebu.uoregon.edu/textbook/se.html


The following link points to a talk by Darren Depoy  which  is a very clear and instructive introduction to the subject:


A couple of lectures from my Introduction to Photometry class can be found here:




A simple definition of the term and scope of the discipline can be found here:

http://www.digplanet.com/wiki/Time_domain_astronomy There are several links to images, videos and references.

A presentation from several scientists from the Harvard–Smithsonian Center for Astrophysics http://dame.dsf.unina.it/documents/DSF_2012.pdf

The following is a link to the International Astronomical Union Working group on Time Domain Astronomy: http://timedomainastronomy.net

V Electromagnetic follow-up of gravitational wave events and GRBs

A very good introduction to Gamma ray bursts in general is this popular book by J Bloom: What are Gamma-ray bursts?  Available from http://www.amazon.com/Gamma-Ray-Bursts-Princeton-Frontiers-Physics-ebook/dp/B004NNUWVM/ref=sr_1_1?s=books&ie=UTF8&qid=1441028997&sr=1-1&keywords=what+are+gamma+ray+bursts

First Searches for Optical Counterparts to Gravitational-Wave Candidate Events, an article publishing the results of the optical coincident observations conducted during the last LIGO S6 scientific run in 2010: http://arxiv.org/pdf/1310.2314v2.pdf

This is a paper about the TOROS project:


Rapid Bayesian position reconstruction for gravitational-wave transients: http://arxiv.org/pdf/1508.03634.pdf

Galaxy Strategy for LIGO-Virgo Gravitational Wave Counterpart Searches: http://arxiv.org/pdf/1508.03608.pdf

Planned search for LIGO FERMI-GBM coincidence in the first advanced LIGO data run  http://arxiv.org/pdf/1506.02628.pdf

Singer’s papers:

The Needle in the 100 deg2 Haystack: Uncovering Afterglows of Fermi GRBs with the Palomar Transient Factory: http://arxiv.org/pdf/1501.00495.pdf

The needle in the hundred square degree haystack: The hunt for binary neutron star mergers with LIGO and Palomar Transient Factory: http://arxiv.org/pdf/1501.03765.pdf

Short duration Gamma ray bursts: http://arxiv.org/pdf/1311.2603v1.pdf

Time domain Astronomy link new!: lightPackage_updated.zip


With Samanta Fuentes (a former graduate student in the group, currently an Astronomy lecturer at UT Pan American) and Dr. Cristina Torres (former student of mine and Research Assistant Professor at UTB who sadly passed away last March) at the Co. Macón site in the Atacama highlands of Salta, in northwestern Argentina.

UTRGV astronomical observatory in its Brownsville location. Soon it will be relocated to Resaca de la Palma State Park See picture below showing the foundation just finished at the park on 7/29/2015

The housing of the  TORITOS telescope at the Macon site in the Atacama region of Northwestern Argentina.