Comet PANSTARRS closest to Earth on July 14th

 

Comet PANSTARRS, C/2017 K2, will be closest to earth on 14th July 2022. The comet at its closest to earth will have a distance of 1.8AU or 269,276,167km in the constellation of Ophiuchus, this distance puts the comet beyond the planet Mars orbit.. The comet is bright enough to be seen in binoculars and small telescopes, the comet has a magnitude of 8. The comet PANSTARRS is well placed for observation, at the time of Sunset the comet will have an altitude of 45 degrees from the horizon, this gives plenty of time to observe, the comet will set at 3:45am.

Comet PANSTARRS, C/2017 K2, is easy to spot in the sky thanks to its closeness to the M10 globular cluster. The comet will be well within the field of view of binoculars, 20X80, until 18th July. Globular cluster M10 is a bright object at 6.6 magnitude, once M10 is the field it won’t be difficult to spot the fuzzy comet . The size of the comet will be roughly the size of M10. 

On 15th July the Comet PANSTARRS, C/2017 K2, will be closest to M10 with a separation of 25 arc minutes. At this small separation the comet and the globular cluster will be in the same field in the telescope, making it a wonderful sight and also to compare the brightness and size of the comet. Hope you all get a chance to view and photograph the comet. 

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Best Times to See Milky Way Galaxy from India

The Milky Way is one of the brightest and famous arms of our galaxy. This is in the region of Scorpius and Sagittarius constellations, this region is also the center of our galaxy. It is a magnificent view when seen under dark skies away from the city light pollution. The Milky Way will appear as a hazy band in the sky, rich with stars, with the brightest region at Sagittarius and dimmer toward north. Many people mistake it for clouds, if you get the doubt, wait for some time and the Milky Way will move along with the stars.

The band of the Milky Way extends from constellations Sagittarius, Sagitta, Cygnus, Cassiopeia to Perseus in the north. To enjoy the full Milky Way band, a place with an unobstructed view of the horizons is essential.        

The Milky Way will be in opposition in the middle of June, that means as the Sun is setting in the west, the Milky Way will be rising in the east. June and July are the best months to enjoy the Milky Way all through the night. I thought making this list of rise, meridian transit and set times of the Milky Way would be useful, so I made one.

Here are the Times for viewing the Milky Way.  

June 15: The Milky Way will rise at 7pm, it will reach meridian, highest altitude in the sky, at midnight and the Milky Way  will set at 5:30am. The Milky Way will be visible all night. 

July 15: The Milky Way will rise at 5pm, reach meridian, highest altitude in the sky at 10:30pm and the Milky Way will set at 3:45pm.

August 15: Milky way will be at meridian, highest altitude in the sky at 8:30pm and the Milky Way will set at 2am.

September 15: By the time the Sun sets, the Milky Way will be at meridian, highest altitude in the sky and it will set at midnight.

October 15: Milky Way will set at 9:30pm.

November 15: Milky Way will set at 7:30pm.

The Sun will be in Sagittarius in December so the Milky Way is not visible. 

Jan 15: The Milky Way will rise at 5am, in twilight.

Feb 15: The Milky Way will rise at 3am.

March 15: The Milky Way will rise at 1am.

April 15: The Milky Way will rise at 11pm and will reach meridian, highest altitude at 4:30am.

May15: The Milky Way will rise at 9pm and it will reach meridian, highest altitude at 2:30am.

As the best months to view the Milky Way galaxy are in the months of June and July, this will make it difficult for south India due to the arrival of Monsoon. To see the band full night or to photograph the band, it is better to move to places where the monsoon has not yet reached. 

You can use the list when going on a trek in a remote place. Check the times during the month and enjoy the view of the Milky Way. 

     

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Sunday Activity at ABAA: Talk on James Webb Space Telescope

After closing three times due to lockdowns and weekend curfews, ABAA is now back to meeting and conducting activities on Sunday evenings at Planetarium. Last Sunday at ABAA there was a talk on the James Webb Space Telescope given by Ravindra Aradhya, President of ABAA.  This was the part one of the series and concentrated on the optics of James Webb Telescope. The idea behind the talk was on how Amateur Astronomers can relate their making of telescopes with JWST. 

As all telescope makers know, the first and most important part is selecting and buying glass blanks. The selection of glass blanks is done based on the need, thermal expansion is one most important of all the criteria. From Speculum metal, used by Newton and William Herschel, Plate glass, a familiar glass to all amateurs, Pyrex used by many amateurs and observatories to Zerodur used by observatories. The talk covered in detail on the advantages and disadvantages of each type of mirror. 

Beryllium used in the making of the James Webb Space telescope was chosen again with the same criteria. The ability of Beryllium to keep the optical shape intact in different temperatures, this is something all Amateur Telescope Makers (ATM) can relate to and has first had experience in that. 

The next concern is the weight, Beryllium was chosen keeping this also as priority. At ABAA members are very familiar with J. Texerea’s mirror diameter to thickness ratio of 1:6.  This is followed for smaller mirrors but the ratio of 1:10 is considered from larger mirrors. This is done to reduce the weight of the primary mirror. For observatory class mirrors, weight is reduced with hollow mirrors with honeycomb support. We can see this kind of mirror used in Hale telescope at Palomar Observatory. 

After covering the topic of choice of glass and weight reducing methods in mirror making the talk covered in detail on the shape of the James Webb Space Telescope, the Hexagon, The geometry and advantages of multi mirrors with Hexagon mirrors was discussed in detail. When it comes to aligning the mirrors, amateurs can understand the importance and difficulties in collimating a telescope. Many were fascinated to know that the hexagon mirrors are already being used in keck telescopes

Next was on the topic of type of telescopes and amateur astronomers know the two kinds of optics most used, the Newtonians and the Cassegrains. The optics and light path was discussed in detail and members could relate the light path in James Webb telescope. Little more time was spent on understanding theThree-mirror anastigmat optics of James Webb. 

It became easier for members to relate their telescope making experience of grinding, polishing and testing. The method of polishing, difficulties and the precision is something that amateur telescope makers are too familiar with. Members now could appreciate and admire the engineering that went into making of JWST.

The surface error that was allowed and achieved for JWST mirrors was 20 nanometers. This number does not make much sense, it's just a number. Until we convert the 1.3 meter segment into nanometers, this will be 1,300,000,000 nanometers, now there were a lot of raised eyebrows in the room. The deformity on the surface should not exceed 20 nanometers at temperature of 40 kelvin (-233 C). To visualize this, our DNA is just 2 nanometers in diameter. Members and audience were excited to realize how small an error astronomers and amateurs work on.

Finally the topic of coating was discussed. Amateur telescope makers, after polishing and testing their mirrors, send the mirror for aluminum coating. Different kinds of coating 

and their applications were discussed. The sliver, aluminum and gold coating is used for different wavelengths. Since JWST is going to study mainly in InfraRed, gold is the best choice. The talk later covered briefly the process of coating mirrors.

         

 

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