Astronomical Events

Comet C/2021

Comet C/2021 A1, now known as Comet Leonard, was discovered in January 2021 by a researcher Greg Leonard. It has a hyperbolic orbit and its journey here from deep space is estimated to have taken about 35,000 years. It will pass near Earth around Dec. 14, when it may be visible with binoculars or possibly even without them. We observed it on Nov. 25 with the HCT (IIA, Hanle) and estimate its brightness as 8th magnitude.

The comet demonstrates a very long tail – actually longer the HCT FOV (10’x10’). The cometary coma is asymmetric. Applying different enhancement techniques to the original images of the comet to make the faint structures visible, we have revealed two jet-like structures (marked by red arrows). These jets form the asymmetric cometary coma – in R filter (which reflects mostly dust) the coma is the usual oval shape, while B and V filters reveal mostly gas – that is why the coma shape is so different in these filters: the jets on both sides (marked by red arrows) create the triangular coma shape.

Intensity maps of comet C/2021 A1 Leonard in B filter. Left: image to which a division by 1/ profile was applied (Samarasinha & Larson 2014); Right: image processed by a rotational gradient method (Larson & Sekanina 1984).

RGB: We have created an RGB – a true colour – image by co-adding the images in B, V and R. As the comet gets closer to the Sun, the nucleus of the comet gets hot, more of the ices melt and diffuse away from the surface, creating an extended, gas-rich cloud known as a coma. Sunlight striking the coma pushes the dust particles out of the coma and away from the Sun, creating a yellow/white tail: a dust tail. But coma has also gases created by sublimated ices like dry ice (solid CO2), methane (CH4), ammonia (NH3), and carbon monoxide (CO): these gases are mostly hydrogen, oxygen, carbon, and nitrogen. Two molecules that are of particular interest are cyanide/cyanogen (CN: a carbon-nitrogen bond) and diatomic carbon (C2: a carbon-carbon bond), and that is what gives the green colour to the coma: the Sun's UV light excite the electrons inside it, causing them to emit a green glow when they drop down in energy. Coma’s green colour is an indicator of a combination of things:
• that the coma contains large amounts of CN and C2 molecules,
• that the comet is active (outgassing) and warm (close to the Sun), and
• that the potential for an eruption or the comet's nucleus splitting apart is at its highest.
Observers: Margarita Safonova and Kiran B.S. (IIA). Image manipulation: Margarita Safonova, Bharat Chandra (IIA) and Olexandra Ivanova (Astronomical Inst. Slovak Academy of Science, Slovakia).

Comet C/2017K2 (PanSTARRS)

In the framework of our program of Oort cloud comets observations, we have observed this interesting comet, assumingly the brightest comet ever detected -- it was even called the “Comet of the Week” on June 6 last year. It was discovered in 2017 by the Pan-STARRS program at a distance beyond Saturn (16.1 au to the Sun) and it was already active with 130,000-km-wide coma (10 times Earth's diameter).

Some comparisons have already been made with the giant comet Hale-Bopp, which flew by in 1997 and is considered one of the brightest comets of modern times. However, it's still too early to tell if K2 truly is of a similar size or if it will shine as bright as Hale-Bopp. It is almost certainly a dynamically old Oort spike comet which has already visited our planetary zone during its previous perihelion passage millions of years ago. While the comet approaches its perihelion on December 20, 2022, it is the target of numerous studies because the long-term monitoring data is very valuable and helpful in studying the activity mechanism of comets at different heliocentric distances from the Sun. The comet should certainly reach naked-eye brightness, perhaps even 5th magnitude.
We have observed it on 10th September in 3 filters: B (3x300sec), V (4x240sec), and R (4x120sec) to create the RGB – the `true’ colour image. Our observations revealed extended 1.2’-wide coma and at least 5.5’-long tail. At its distance of ~5.412936 AU, the coma is ~282,660 km, and the tail is about 1 million 300 thousand-km long. Interestingly, last September the length of the tail was about 800,000 km.

Observers: Margarita Safonova and Sujith D. S.
Image manipulations: Margarita Safonova, Igor Luk’yanyk and Bharat Chandra.

The light to the right of the comet is the spillover from the overbright 4th magnitude star epsilon Herculis.

Posted on: 29th Sep 21

There is no dearth of spectacular comets in our skies this fall. One of them is the comet C/2020M3 (ATLAS), called so because it was discovered in 2020 (in June) by the Asteroid Terrestrial-Impact Last Alert System (ATLAS). It had passed the perihelion on 25 October, and was closest to the Earth at just 2.9 light-minutes away on November 14th. It turned out to be a periodic comet, but its next visit will be only in 2159. Surprisingly, this comet does not have a pronounced tail, but has an extended coma, about 340,000 km in diameter by some estimates: almost the distance from Earth to the Moon.

We have taken images of this comet on HCT, Hanle on November 17th in B, V, R and I filters (top row of images). It is much brighter in I filter which suggests that it has lots of dust in the coma (the 60-sec I image shows the extent), but only a spectroscopic analysis can reveal the actual details of the emission. Each image shown here is 10x10 arcmin in size.

Observers: Margarita Safonova and Pramod Kumar (IIA)
Image manipulations: Marek Husarik and Oleksandra Ivanova (Astronomical Institute of Slovak Akademy of Science, Slovakia).

Astronomical Event: Penumbral Lunar Eclipse

Event Time in Bangalore
Penumbral Eclipse begins - 10 Jan, 22:37:44 (10.37 pm)
Maximum Eclipse - 11 Jan, 00:40:02 (12.40 am)
Penumbral Eclipse ends - 11 Jan, 02:42:19 (02.42 am)


Comet C/2019 Q4 (Borisov)

The comet C/2019 Q4 (Borisov), or 2I/Borisov, was discovered just less than 2 months ago, and already gained enormous interest as it turned to be from outside the Solar System (SS). IAU Minor Planet Center wrote: ‘Based on the available observations, the orbit solution for this object has converged to the hyperbolic elements, which would indicate an interstellar origin.’ The other indications are its much higher velocity than usual SS comets, at more than 30 km/sec, and the orbit nearly at a right angle to the ecliptic. This is the first interstellar comet in our times, and the second interstellar object; the first was asteroid Oumuamua that passed through the SS in 2017.

The call for observations went out to everyone all over the world because the more observations are performed, the more precisely the orbit can be determined. We have observed the comet with the HCT on 13th and 14th September with the Himalayan Chandra telescope (HCT), Hanle (MPC code: N50) in 3 filters V, R and I. Each exposure was only 100 sec because it is moving so fast, thus we have combined the exposures in every filter to increase the signal. We show here images in three filters to show the difference in the comet appearance in different bands: in V the tail is longer and straight, while in R and I the tails are shorter and spread out. V image is a stack of 9 frames; R image is a stack of 7,and I image is a stack of 3 frames.

On 13th September, the comet was at 3.389 AU at the start of observations and at 3.388 AU at the end. On 14th it was already at 3.367 AU, covering angular distance of 0.53 deg in just one day. It is interesting to note that, according to other observers as well, the comet colours are the same as our SS comets colours indicating that chemistry is no much different in other solar systems.
Our observations (RA, Dec and UTC) are published in the Minor Planet Centre Electronic Circular (M.P.E.C. 2019-T169, issued 2019 October 9), and will be used for refining the orbital parameters.

Observers: Margarita Safonova and C.G. Anaswar.
Image manipulations: S. Akaash and Bharat Chandra.

Figure: RGB image of the comet Borisov
The RGB image is a combination of frames taken in V, R and I filters, each of ~300 sec combined exposure, and aligned on the comet's optocentre.


We conclude our observations of comet 46P/Wirtanen with December 2018 images taken on the 2-m HCT, Hanle,
and on the 1.3-m JCBT, Kavalur.

The comet has reached the perihelion on December 12, 2018. The movie of the comet motion was made from 51
R-band frames, each of 6 sec, taken on December 13, 2018.

The RGB image is a combination of frames taken in R, V and B filters, each of ~180 sec exposure, and aligned on
the comet's optocentre. The comet frames were taken with the non-sidereal tracking of the comet.

HCT: Margarita Safonova, Kiran B. S. and Rakesh C. M.
JCBT: Ayaush Keshava and Venkatesh Shankar.
Image manipulations: Rekhesh Mohan (movie) and Bharat Chandra (RGB).


This 600 sec R-band frame was taken in the Keystone mode of the HCT with non-sidereal tracking - where the comet stays in the centre and the stars trail. The saturated star in the image is the 8th V mag star Tyc 6431-211-1. The Keystone mode-compatible files have been generated by Firoza Sutaria using the ephemeris data for the comet from NASA JPL.

Observers: Margarita Safonova, Binukumar Nair and Kiran B.S.


The following images of the comet 21P/Giacobini-Zinner were taken on October 09, 2018 in three bands: R, V and B. The comet
is moving away from the Sun and is currently at a distance of 1.3 AU from the Sun, getting fainter.

Observers: Margarita Safonova, Binukumar Nair and Kiran B.S.


The following images of comet 21P/Giacobini-Zinner and comet 46P/Wirtanen were taken in September 2018 on the HCT, IIA.

21P/G-Z is a periodic Jupiter family comet with period of ~6.54 years. It is the parent to the annual October Draconid meteor shower. The perihelion occurred this year on September 10th and was the closest for the last >70 years. This comet is called a green comet because some images show the comet's coma/tail as a green colour indicating the comet has cyanogen and diatomic carbon: gases that glow green in sunlight. This RGB image is a combination of frames taken in R, V and B Bessel filter, each of 20 sec exposure, and aligned on the comet's optocentre.

46P/Wirtanen is also a Jupiter family comet with period of about 5-6 years. It will reach perihelion on December 12, 2018, and perigee on December 16, and is expected to reach naked eye brightness: visual magnitude of 3.5 to 6. This passage of comet Wirtanen near the Earth will be the 10th closest approach of a comet in modern times. These two images are taken on 10th and 20th September 2018, with R-band 60 and 40 sec exposure, respectively.

These comets are observed as part of world-wide 4*P Coma Morphology Campaign (, organized by the Planetary Science Institute, looking for the features like jets, outflows as well as rotation of the nucleus, etc.

Observers: Margarita Safonova and Kiran B. S.


Following images of comet 41P/Tuttle-Giacobini-Kresak were taken on 31st March 2017 with the Himalayan Chandra Telescope (HCT) at the Indian Astronomical Observatory (IAO) at Hanle, by Dr. Margarita Safonova and Mayuresh Sarpotdar, Indian Institute of Astrophysics, Bangalore.

18:00:41.00UT, 5 sec, R band single exposure.
Observers: Margarita Safonova, Mayuresh Sarpotdar and Pramod Kumar

Comet movie made out of 10 5-sec R band exposures.
Observers: Margarita Safonova, Mayuresh Sarpotdar and Pramod Kumar


Milky Way in August 2015

Milky Way Observed from Kodaikanal Solar Observatory, using DSLR Camera (D5200)
Observers & Photographers: Ramya Anche & Mayuresh Sarpotdar
ISO : 3200
F# : 3.2
Exposure : 13 sec
Stack of 50 frames of 13 seconds each. Total exposure : 10 mins 50 seconds.


Nova Sagittarii 2015 No. 2
28 March 2015

Nova Sagittarii 2015 No. 2 Observed from IIA Bangalore, using digital Cameras ( Canon SX 150 and Canon 1100D)
Observers were: Prasanna Deshmukh & Mayuresh Sarpotdar


Comet Lovejoy C/2014 Q2
11 Jan 2015

Comet Lovejoy Observed from IIA Bangalore, using digital Cameras ( Canon SX 150 )
Observers were: Prasanna Deshmukh, Joice Mathew, Mayuresh Sarpotdar


Comet Siding Spring
October 2014

Comet images taken on 18th October 2014, Himalayan Chandra Telescope (HCT), as part of the world-wide campaign to monitor comet's encounter with Mars.
Observers were: Sreejith, Joice, Mayuresh, Pramod; Ephemeris calculations: Firoza Sutaria; Data Reduction: Margarita Safonova; PI: Jayant Murthy.

Above image was processed by image enhancement technique by Nalin Samarasinha (Planetary Science Institute, USA) to extract the underlying features.


Comet ISON
September 2013

C/2012 S1, also known as Comet ISON, is a sungrazing comet discovered on 21 September 2012 by Vitali Nevski and Artyom Novichonok . The discovery was made using the 0.4-meter (16 in) reflector of the International Scientific Optical Network near Kislovodsk, Russia and the automated asteroid-discovery program CoLiTec. Precovery images by the Mount Lemmon Survey from 28 December 2011 and by Pan-STARRS from 28 January 2012 were quickly located. Follow-up observations were made on 22 September by a team from Remanzacco Observatory in Italy using the iTelescope network. The discovery was announced by the Minor Planet Center on 24 September. Observations by SWIFT suggest that C/2012 S1's nucleus is around 5 kilometers (3.1 mi) in diameter.

C/2012 S1 will come to perihelion (closest approach to the Sun) on 28 November 2013 at a distance of 0.012 AU (1,800,000 km) from the center point of the Sun. Its trajectory is nearly parabolic, which suggests that it may be a dynamically new comet coming freshly from the Oort cloud. On its closest approach, C/2012 S1 will pass about 0.0724 AU (10,830,000 km) from Mars on 1 October 2013, and it will pass about 0.429 AU (64,200,000 km) from Earth on 26 December 2013.

  • COMET ISON Images from 1.3m Telescope at Vainu Bappu Observatory (VBO), Kavalur, India

  • Comet ISON Images from Himalayan ChandraTelescope (HCT) at the Indian Astronomical Observatory (IAO), Hanle

  • Comet ISON Movies from Himalayan ChandraTelescope (HCT) at the Indian Astronomical Observatory (IAO), Hanle

  • Useful links on Comet ISON

  • Eyes on ISON Campaign, India

  • Your Guide to Track ISON Comet: (BangaloreMirror article)
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    Comet ISON
    19 Nov 2013

    Comet ISON Observed from IIA Bangalore, using digital Cameras ( Canon SX 150 )
    Observers were: Prasanna Deshmukh, Ramya Manjunath, Mayuresh Sarpotdar