Research & Education

Giant Oort Cloud Comet C/2014 UN271 (Bernardinelli-Bernstein)

Ernesto Guido — Wed, 30 Jun 2021 12:05:53 +0000

Giant Oort Cloud Comet C/2014 UN271 (Bernardinelli-Bernstein)

Ernesto Guido Wed, 06/30/2021 - 12:05

On 2021 June 19, the circular MPEC 2021-M53 of Minor Planet Center announced the discovery of an asteroidal object by astronomers P. Bernardinelli & G. Bernstein (University of Pennsylvania) that they found in CCD exposures obtained with the 4.0-m reflector at Cerro Tololo Interamerican Observatory in the course of the "Dark Energy Survey", and which they reported as a previously unknown member of the Oort Cloud. The reported astrometry was spanning from 2014 Oct. 20 to 2018 Nov. 8. The new object was designated 2014 UN271. It was hidden among data collected by the 570-megapixel Dark Energy Camera (DECam) mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile and was announced only now because, in the words of one of the discoverers, "finding TNOs with DES is a massive computational problem (my PhD was solving this problem). The search itself took 15~20 million CPU-hours, and the catalog production from our 80,000 exposures probably took more than that!"

According to the orbit calculated using data from 2014 to 2018, this object is likely to be a comet from the inner edge of the Oort Cloud. But 2014 UN271, despite its typically cometary orbit, appeared completely stellar in these archival images when it moved from 29 to 23 AU (for comparison, Pluto is 39 au from the Sun, on average). Below a simulation (made by T. Dunn) of the orbit of comet C/2014 UN271 showing it path in the Solar System from 1985 to 2049.

A few days after the discovery announcement, 2014 UN271 has been found to show cometary appearance in new CCD images obtained by observers at station codes L81 & K93.Basically this object, that was first seen as an asteroid of magnitude ~22 by DES in 2014 at a distance of 29 AU, approaching the Sun was growing his coma and tails. As of June 2021, it was 20 AU from the Sun shining at a magnitude ~20.After the discovery of the cometary coma, the new comet has been designated C/2014 UN271 (Bernardinelli-Bernstein). This comet will reach perihelion, its closest point to the Sun, in January 2031 at about ~11 AU away from the Sun.

The absolute magnitude of C/2014 UN271 measured in DES images dated back to 2014-2018, has a value of H = 7.8 which suggests the body could be around 100–200 kilometers across. This value for the size of this comet is valid if we assume there was no contribution from a dust coma in that images. For scale the nucleus of comet 67P/Churyumov–Gerasimenko (that was the destination of the European Space Agency's Rosetta mission) is about 4km in diameter while nucleus of comet Hale–Bopp was about 60±20 kilometres in diameter. According to these data and with a reasonable degree of certainty, C/2014 UN271 it’s the biggest comet that we’ve ever seen!

Despite some exceptional features displayed by this comet, its considerable distance to perihelion should limit the peak magnitude to fairly modest values. Anyway, as always with comets, the future magnitudes reported here are only indicative. Below you can see a graph generated using the software Orbitas and showing the predicted magnitude (in red) versus its distance from the Sun.

We have been able to image this special comet on 2021 June 27 at 10UT from X02 (Telescope Live, Chile) with our CHI-1 telescope that is a 0.61-m f/6.5 astrograph + CCD. Stacking of 13 unfiltered exposures, 240 seconds each, clearly shows the coma developed by this object (Observers E. Guido, M. Rocchetto, E. Bryssinck, M. Fulle, G. Milani, C. Nassef, G. Savini, A. Valvasori). (click on the images below for a bigger version; made with TYCHO software by D. Parrott).

We had the pleasure of seeing our image featured in the article dedicated to this comet by the New York Times and written by science writer R. G. Andrews.

There is no doubt that this comet will be one of the most observed by astronomers for years to come.

Recurrent Nova RS Ophiuchi is in OUTBURST

Ernesto Guido — Mon, 09 Aug 2021 12:52:59 +0000

Recurrent Nova RS Ophiuchi is in OUTBURST

Ernesto Guido Mon, 08/09/2021 - 12:52

Recurrent Nova RS Ophiuchi is in OUTBURST!

It is news of the last few hours that the recurrent nova RS Ophiuchi is in outburst. For first time in 15 years, the famous recurrent nova RS Ophiuchi has erupted into naked-eye visibility. The last large outburst of RS Oph occurred in Feb. 2006, when it reached visual mag 4.5.

As late as August 08.48, 2021, the star was still around magnitude 11.5, where it spends most of its time with only minor fluctuations. But just few hours later it was found in outburst by two amateur astronomers.

This outburst has been discovered by K. Geary (Ireland) that reported it at visual magnitude 6.0 on Aug. 8.93 UT and independently by A. Amorim (Brazil) who provided the following visual magnitude estimates: Aug. 8.91, 5.0 (10x50 binoculars); 8.95, 5.0 (naked eye).

Here at Telescope Live, thanks to our telescopes located all over the world, we have been able to perform very soon some follow-up of RS OPHIUCHI 2021 outburst. We imaged it through our TEL 0.1-m f/3.6 astrograph + CCD located in the Heaven's Mirror Observatory, Australia (MPC code Q56). On our images (see below) taken on August 09.42, 2020 we can confirm the presence of an optical counterpart (approximate R-filtered magnitude about +4.8; images were saturated in 10-second exposures).

by Ernesto Guido, Marco Rocchetto, Adriano Valvasori, Chantal Nassef

Observing the NOVA SAGITTARII 2021 No. 2

Ernesto Guido — Fri, 07 May 2021 14:57:23 +0000

Observing the NOVA SAGITTARII 2021 No. 2

Ernesto Guido Fri, 05/07/2021 - 14:57

Following the posting on the Central Bureau's Transient Object Confirmation Page about a possible Nova in Sgr (TOCP Designation: PNV J17581670-2914490) we performed some follow-up of this object through a TEL 0.6-m f/6.5 astrograph + CCD located in the El Sauce Observatory in Chile and operated by Telescope Live network (MPC Code X02).

This transient has been discovered by Andrew Pearce at 8.4 mag (unfiltered) on 2021-04-04.825 UT using a Canon 1100D DSLR camera with a 100mm f/2.8 lens. Total exposure time was 20 seconds (2 x 10s images stacked). Rob McNaught reported non-detection on 2021-04-02.776 UT (unfiltered limiting mag 11.0).

Our confirmation image

On images taken on April 06.40, 2021 we can confirm the presence of an optical counterpart with B-filtered CCD magnitude +8.955 (R-filtered & V-filtered images were saturated in 5-second exposures) at coordinates:

R.A. = 17 58 16.08, Decl.= -29 14 56.4

(equinox 2000.0; Gaia DR2 catalogue reference stars for the astrometry).

An animation showing a comparison between my image and the archive POSS1 plate (1996-09-12).
Made with TYCHO software by D. Parrott.

According to ATel #14513, K. Taguchi et al. obtained a spectrum of this transient on 2021-04-05.828 UT using the fiber-fed integral field spectrograph mounted on the 3.8-m Seimei telescope at Okayama Observatory of Kyoto University. Their spectrum shows Balmer lines, Fe II lines, and the Na I D line. According to their spectrum and the brightness, they conclude that this object is a classical nova (with a spectrum similar to those of the slow nova V1280 Sco in the early stage).

Below is part of the discovery image by A. Pearce showing the nova. The bright stars to the top right are gamma 1 and 2 Sgr. South is to the top and east to the right. (Click on it for a bigger version)

Credit: A. Pearce

This nova has been designated N Sgr 2021 No. 2 (with permanent GCVS designation V6595 Sgr).

1998OR2 - A close reminder

Giorgio Savini — Fri, 12 Jun 2020 12:30:20 +0000

1998OR2 - A close reminder

Giorgio Savini Fri, 06/12/2020 - 12:30

Near-Earth Asteroids are a favourite of popular astronomy often due to their association to cataclysmic events and consequent mass extinctions, with smaller recent reminders (Tunguska, Chelyabinsk or the recent explosion over the Bering Sea) of the raw power of the kinetic energy of these “pebbles”.

While the number of asteroids which have been detected and "labelled" in the Solar system approach a million units, there is a small portion (just over 20000) the orbit of which brings them periodically relatively close to the Earth (so-termed Near Earth Asteroids or Near Earth Objects).
These distances are close enough in range for astronomers to switch from Astronomical Units (1 AU - the average distance between the Earth and the Sun) to Lunar Distance (LD - the average distance from the Earth to the Moon - 400 times smaller) or in the extremely close approaches, to Earth radii.
In this asteroid family, few are bigger than asteroid (52768) or 1998OR2 with an approximate diameter of 2 km. This NEO was discovered by the Near-Earth Asteroid Tracking program at NASA's Jet Propulsion Laboratory in July 1998 and it has been monitored ever since. With all the data gathered, precise orbital parameters and trajectory have been reconstructed allowing for accurate predictions of its passes in the future.

The orbit of 1998OR2 has a high eccentricity (0.573), bringing it further out than the orbit of Mars (FIG), but at approximately 10 UT on the 29th of this past April, it came as close as 16 lunar distances to Earth as it became very visible to small and medium telescopes. In previous observations, rotational lightcurves measured a rotation period of the asteroid of about 4.1 hours with a brightness amplitude of 0.2 magnitudes. The albedo assumed is that of a standard stony asteroid (0.20).

The next closest pass will be in 2079 at just over 4 LD. It is expected that any risk of future impacts on Earth is likely to be in the timescale of thousands of years. For now, the closest approach of a large asteroid (~300m) predicted to date is in 2029 by Apophis which should come in the range of geostationary satellites at 30000km (less than 1/10th of a lunar distance). While this is still a considerable distance, it is a reminder of the level of precision required in such measurements and calculations. As a thought experiment, consider that at the Earth's orbiting speed of 30km/s it is equivalent to predicting a "miss" of 20 minutes 9 years from now.(*)

On the 18th of April it was radio-imaged by the Arecibo Observatory showing the presence of a large crater as well as other features.

We used Telescope Live data to observe 1998OR2 on its closest pass as it reached a bright magnitude (lower than 11) speeding across the southern sky.

Observations were taken with 3 sets of 10s exposures at 1-minute cadence on a Lum filter at 1h and 15 minutes between sets.

(*) This is just a thought experiment, as the trajectory is outside of the Earth's orbit (does not cross it).

Using Telescope Live Remote Telescopes for Teaching Astronomy at University Level

Giorgio Savini — Fri, 07 Feb 2020 14:11:07 +0000

Using Telescope Live Remote Telescopes for Teaching Astronomy at University Level

Giorgio Savini Fri, 02/07/2020 - 14:11

At the UCL Observatory at Mill Hill (London) we have a number of telescopes (20 to 80cm) that we use for teaching purposes and with which we conduct research in a number of fields. As Director of the UCLO I coordinate the teaching activities for our Astronomy students and I love the opportunity to collaborate with Telescope Live as it opens the amazing possibility of accessing the Southern Hemisphere for our students and provide multiple different timezones under one single provider.

Our students use Telescope Live for a number of projects, from photometry of exoplanet transits to cataclysmic variables, searches of supernovae and over transients as well as Near Earth asteroid search and monitoring. The key thing that students face is calculating (given the available information on the telescope capabilities) the expected amount of time and number of images required to observe given objects. The Telescope Live platform is great as it provides confirmation of visibility of targets and allows students to plan and position their timed observation precisely.

Once the data is downloaded from the platform, students either use existing code we have at the Observatory or create their own to extract photometry and light curves as well as perform differential comparisons to detect transients and moving objects. In Year 1 we teach basic image processing including steps such as dark-subtraction and flat field corrections. Acquiring images from Telescope Live, these steps are then automated by a simple data pipeline, which is great as it allows students to focus on the science. Resulting data from image analysis is then included in a variety of student projects and in a few cases can lead to the submission of research papers.

Telescope Live has become an essential part of our teaching as we include its usage in a number of taught modules. In addition, research student projects apply for observing time in a fashion similar to professional astronomers, providing experience in proposal writing. Our principal use will include (but not limited to) monitoring of exoplanet transit timing, asteroid observations and optical follow-up of gravitational wave events.

We also look forward to working with Telescope Live to help develop their future observing capabilities including rapid imaging and spectroscopy as well as structured pipelines for data analysis and storage by testing new equipment and pipelines on our telescopes.

Comments

Charles Graham Taylor

A fascinating insight into the moderm astronomy syllabus.

Edited:

Following Exoplanets with Telescope Live to Refine their Ephemeris

Hamish Caines — Fri, 03 Jan 2020 15:00:00 +0000

Following Exoplanets with Telescope Live to Refine their Ephemeris

Hamish Caines Fri, 01/03/2020 - 15:00

Distributed networks of robotic telescopes have the power to make a significant contribution to the scientific community, in a variety of fields. As part of the Telescope Live collaboration with the University College London Observatory (UCLO), PhD student Hamish Caines has been working to develop pipelines and processes to manage the efficient use of the Telescope Live network to make these contributions. Also working on this project are Professor Giorgio Savini, Director of UCLO, and Dr Marco Rocchetto, one of the key developers behind Telescope Live. The first area of interest we have identified is the study of Exoplanetary Systems.

An Exoplanetary System is comprised of a host star and at least one planet in orbit around it. Several thousand of these planets have been discovered since the first in 1992, and the easiest way to observe many of these is through the transit method. If an exoplanet’s orbit is aligned correctly, it will regularly pass between us and its host star. When this happens, the brightness of the star drops slightly, similarly to how the sky gets dark during a solar eclipse this is called a transit. However, the drop in brightness that results from an exoplanetary transit is much smaller than the drop we see during a solar eclipse.

If an exoplanet with an atmosphere transits its host star, in addition to light being blocked by the planet, some will filter through the atmosphere, leaving traces of its components. Specific elements and molecules have specific chemical signatures that we can search for and then measure the strength of. This allows to determine and quantify the composition of the planet’s atmosphere, this is technique called transit spectroscopy.

The ARIEL mission is an M-class European Space Agency mission, led by Professor Giovanna Tinetti of UCL. The ARIEL mission will observe 1000 extra-solar planets using photometry and spectroscopy in order to attempt to determine the composition of their atmospheres. It will use transit spectroscopy to do this and therefore will require precise knowledge of the 1000 planets’ transit timings. However, as the mission will not launch until 2028, this precision will degrade significantly, preventing efficient use of the observing time that will be available. In some extreme cases, the uncertainty in any predicted transit time will exceed the duration of the transit itself, making any observation difficult, let alone and efficient one.

As the uncertainty in a predicted transit time grows with time, the easiest way to prevent the uncertainty growing too large is to periodically obtain more up-to-date data for each target. This is where Telescope Live can contribute. Observations of exoplanet transits, which are fixed in time, will require a distributed network of telescopes to cover as much of the night sky as possible, to ensure that we can cover all of the targets in the ARIEL target list.

In addition to the telescope resources, we also require an efficient method for the scheduling of the observations. We need to ensure that the uncertainties for all targets do not grow to be too large, whilst ensuring that we are using the observing time efficiently. To do this, we have tested multiple sets of selection criteria by simulating the acquisition of the observations from today until the mission launch and evaluating the resulting performance. We do this by examining how successful the criteria were at maintaining the timing uncertainties within the desired limit, and how much observing time was used.

In addition to testing the selection criteria, we also tested the telescope configurations used in the data acquisition, starting from the current Telescope Live network. We then added more telescopes to the network and re-ran the simulator. We can therefore quantify the impact of adding telescopes in different areas of the globe, which is useful information that may be used to inform future decisions regarding the expansion of the Telescope Live network.

Following our work on determining the most efficient scheduling method for this data acquisition, we have developed a scheduler outside of the simulator that generates observation schedules for a real network of telescopes. The next step is to develop an algorithm for this scheduler to interact with the Telescope Live scheduler via an API, allowing automated scheduling of exoplanet transit observations in a way that does not interfere with other users of the network.

Finally, once we have obtained some data, we will look to develop automated pipelines for the processing of the time-series data, and the transit light curve fitting routines that will extract the timing data that we require. In addition, we are continuing to explore other research areas that will benefit from the use of the Telescope Live network.