Comet C2015 V2 (Johnson)

Just after midnight 30 April 2017.Composite stacked image using the 127mm Refractor with 0.8x focal reducer and field flattener and Canon 600d DSLR. The image is a section of a wider-field and is the composite of stacked 10x 1 minute exposures taken at ISOs 1600, 3200 and 6400.

Comet C2015 V2 (Johnson) was discovered in 2015 by Jess Johnson (Catalina Sky Survey) and will leave the Solar System on a hyperbolic orbit. - credit Wikipedia.

" A comet is a minor member of the Solar System which travels around the Sun in an orbit that is generally more eccentric than the orbits of the planets. Comets typically have three parts : The 'nucleus', the 'coma' and the cometary 'tails'. 

The nucleus is the solid portion of the comet. The size of cometary nucleii vary. Most are less than a kilometer in diameter but some of the more spectacular comets are larger.  Hale Bopp, probably the best comet seen from the UK in the last 200 years was estimated to have a diameter between 40 and 80 kilometers. The cometary nucleus, described by the astronomer Fred L Whipple in 1951 as a 'Dirty Snowball" is thought to be made up from dust and frozen; water ice, carbon monoxide, carbon dioxide, methane and ammonia.

The  coma is the most obvious part of the comet when it is close to the Sun. The coma is a diffuse luminous nebulous cloud of gas and dust that surrounds and hides the cometary nucleus from sight. It is formed by the sublimation of ices and the ejection of dust particles from the nucleus. The coma is densest closer to the nucleus where the material being released is at its highest. The sublimation is driven by the warming of the nucleus by sunlight and so the size of the coma varies with distance from the Sun. The luminosity of the coma is mainly produced by fluorescence from a variety of carbon, nitrogen,hydrogen and oxygen ions and the reflection of sunlight by dust particles. The coma is extremely rarefied and consequently even faint stars may be seen shining through it. Comas may be circular or fan -shaped.

The cometary tails. If there are tails of gas and dust, they point away from the nucleus in a direction opposite to the Sun.  The tails are only readily apparent when the comet is near to the Sun and usually within two astronomical units (x2 the average distance between the Sun and the Earth). Not all comets have visible tails, but when present, their luminosity is due to both molecular and atomic emission and to the reflection of sunlight. The dust and the gas is forced away from the nucleus by the radiative pressure of the Sun and solar wind interactions. There are two very different types of cometary tail; the plasma or ion tail which is often straight and bluish, consisting of ionized molecules moving at speed and the more strongly curved dust tail. The dust tail shines simply because it is made from billions of tiny solid particles which reflect sunlight.

Comet 2015 V2 Johnson was 152.72 million kilometers from Earth and 259.82 million kilometers from the Sun when it was imaged  just after midnight on the 30th April from the Jodrell Plank Observatory.  The comet was at Magnitude 7.64 and was located at RA 15 degrees 53 minutes 43 seconds and Dec 43 degrees 56 minutes 14 seconds N."

 Kurt Thrust - Director of the Jodrell Plank Observatory

 

Positive and negative images taken from the Observatory showing details of the diffuse fan- shaped coma

 "Most comets move in elliptical orbits (some like Halley's Comet being retrograde). They fall into two distinct classes; 'long period' comets and 'short period' comets. The former are the great majority and have orbital eccentricities very close to unity (1.000 - almost parabolic). The much smaller group of short period comets are regular returnees to our skies following elliptical orbits with the Sun at one focus of the ellipse and at all inclinations to the ecliptic. Most comets reach perehelion (closest point to the Sun) at one or two Astronomical Units (AU) and move within a sphere centred on the Sun. The aphelia (greatest distance from the Sun) of long period comets may extend as far as 50,000 AU with orbital periods as long as a million years or even more. In some cases planetary gravtational effects may make a cometary orbit hyperbolic (ie. where orbital eccentricity is greater than unity), while in others the orbit may be changed into a small ellipse. C2015 V2 (Johnson) will leave our Solar System on a hyperbolic orbit never to be seen again - so when its gone its gone! With every perehelion event, a comet loses material as a result of the intense solar heating and gravitational tidal forces. So eventually short period comets, like the Cheshire Cat, just evaporate away". 

 Archie Mendes - visiting theoretical astronomer at the Jodrell Plank Observatory - Reydon University - 'School of Computer Modelling and Difficult Sums' - author of "Quantity Surveying and Standard Methods of Measurement in Curved Space Time" or "When the Socks come off!"

Sunspot Region AR2651

Testing the pier mounted 127mm Meade Apo-refractor with white light filter. Observed double sunspot on the solar limb - believe this to be Sunspot Region AR2651(false colour)

"The gusting wind and high level hazy cloud, together with the sunspots' location close to the solar limb, made imaging this region problematic.  The pier dampers performed well and were effective in reducing the vibrations created by the wind.  The intermittent cloud however, prevented sharp images of the sunspots being aquired.  The white light filter had not been used since the 'Transit of Mercury' observations and is in need of some urgent refurbishment before further use.  This priority work will be undertaken by our dexterous 'Observatory Instrumentation Engineer and Associate Astronomer' - Jolene McSquint " - Kurt Thrust - current Director of the Jodrell Plank Observatory.

Widefield view of Sunspot Region AR2561 (false colour)

Enlarged view of  spots with faculae showing as brighter surface areas (false colour)

 

Image of the Earth added to show the scale of AR2651. Most spots range in size from about 1,500 km (932 miles) to around 50,000 km (31,068 miles) in diameter. Once in a while, huge sunspots the size of Jupiter show up on the Sun's surface.

The last three above images have benefitted from the applied skills of the Observatory's ' Imaging Team Leader' -  Pipp Stakkert.

The Occultation of Europa

First image from the newly mounted 127mm Refractor, taken from the  Jodrell Plank Observatory

"Last night the weather conditions were far from ideal for astrophotography, with high winds and clouds over Lowestoft, but as Jupiter was shining brightly and the Galilean moon Europa was about to be eclipsed and occulted by the planet, I turned the telescope towards the Jupiter and took the above image using the QHY5-11 colour planetary camera. The recently constructed permanent pier performed vey well in the high winds damping any vibrations very affectively". 

"The Great Red Spot was visible through out the evening's observations, in recent times this anticyclonic storm system within the clouds of the equatorial belt has become redder and smaller in size. This storm has existed since observations capable of seeing it commenced but are we now witnessing the beginning of the end for the Great Red Spot ?"

"An eclipse occurs when the shadow of the planet falls upon the moon. An occultation occurs when the moon moves behind the planet. An eclipse of one of the Galilean moons will occur when the planet is between the sun and the moon, consequently a Galilean moon may disappear from our line of sight whilst some distance from Jupiter's limb, it just depends upon the orbital 3 dimensional geometry and the positions of Jupiter, the Galilean moon and Earth". An occultation occurs when  Jupiter is between the Galilean moon and the Earth on a  line of sight from a given location on Earth".  Kurt Thrust current Director of the Jodrell Plank Observatory.

Building Works at Jodrell Plank

The NEQ6Pro equatorial mount fixed to the top of the newly constructed Lowestoft Pier

Alan Waffles inspects the fine concrete work of his son Barry Waffles

" The Jodrell Plank Observatory has been running in maintenance mode whilst upgrading works have been undertaken by the two man building team Alan and Barry Waffles.  The major project to replace the ageing tripod, supporting the 127mm Meade Apochromatic Triplet Refractor, with a purpose designed and constructed reinforced concrete pier has been completed ahead of schedule.  Our thanks to Alan and Barry for their efforts to ensure the pier was built in the right place,to specification, ahead of programme and within the project budget. The name 'Waffles' will be written in the stars "   Kurt Thrust - current Director of the Jodrell Plank Observatory.

"Due to concerns raised by Mrs. Alice Boon Oxon, both Waffles Construction Ltd. and The Jodrell Plank Observatory wish to confirm that no Sea Eagles were harmed whatsoever during the recent pier construction process". Alan Waffles and Kurt Thrust -14-04-2017

41P/Tuttle–Giacobini–Kresák

Comet 41 P cruising in front of the stars in the constellation Ursa Major or the Great Bear. Taken with the 66mm. Altair Astro Doublet with 0.8x focal reducer and field flattener, Canon 600d DSLR all on a Star Adventurer equatorial mount. 22x30 second lights at ISO1600 with darks and flats stacked and processed using DeepSky Stacker.

This comet is visible currently from the United Kingdom. It is a 'periodic' comet - a comet that orbits the Sun and returns to its innermost point (perehelion) at known intervals. Comet 41 P will reach perehelion at the beginning of April 2017. After this encounter with the Sun it will head back out past the gas giant planets; Jupiter, Saturn, Uranus and Neptune, following an elliptical orbit which will bring it back again in approximately 5.4 years.

The comet will pass Earth at its closest on the 1st of April 2017 when it will be at a distance of 13.2 million miles. You should be able to see this comet with binoculars but it may well be quite faint. It's nucleus is only about 1 mile in diameter.  In the past, this comet has been known to brighten quite unexpectedly so, after dark on the first few nights of April, it is worth looking in a wide area to the west of a line drawn between the Pole Star and the 'pointer' stars in the Great Bear and you just might get to see this comet .

Enlarged Image of 45P  taken at ISO6400 for 10x20 secs

"Comet the Observatory cat likes this one" Kurt Thrust - Director of the Jodrell Plank Observatory.

The Hyades and NGC1647

The Hyades and NGC1647 - two open star clusters in the constellation Taurus - Canon 600D DSLR camera with EOS 18-55mm lens mounted on a Star Adventurer Equatorial Mount

Lowestoft has been experiencing some cloud and moonlight free nights. Because of ongoing construction works the 127mm refractor has been out of action, so what astrophotography has been undertaken has been accomplished using widefield equipment.  As spring heralds lighter evenings Taurus is setting in the west as astronomical darkness falls.

"NGC1647 is an open star cluster of some 90 stars. The cluster was discovered by William Herschel in 1784.  NGC1647 is located to the top left of the above image which was taken from the Jodrell Plank Observatory. On average the stars that make up NGC1647 are 1800 light years distant from our Solar System and 150 million years old. By contrast the Hyades open cluster is closer to us than NGC1647 and made up of much older stars estimated as 625 million years. Consequently, the stars of the Hyades are less densely packed with those on the periphery, in the cluster's halo, probably in the process of escaping the cluster's gravitational influence.  The bright orange star Alpha Tauri or Aldeberan is not part of either star cluster residing much closer to Earth at an estimated 65 light years from the Sun". Kurt Thrust - Director of the Jodrell Plank Observatory.

Credit: Wikipedia

Lunar Ejecta Rays

Super-moon 2015. The impact crater Tycho with bright ejecta rays radiating from the bottom left of this image are easily visible with low power binoculars.

When we look at the full moon through a low power eyepiece on a telescope, the ray systems associated with the very many impact craters are blatantly apparent. The most easly observed is associated with the crater Tycho.  Although there is plenty of evidence for volcanism on the moon, the majority of craters easily visible are related to massive impacts with asteroids which occurred aeons ago. The bright rays emanating from craters were created by the explosive nature of the impact and the ejection of excavated incandescent rock.

I am grateful to the excellent magazine 'Astronomy Now' for focussing my attention on a not so obvious issue:
" Have you ever wondered why the overwhelming majority of lunar impact craters are circular or nearly circular when, statistically, most incoming projectiles would presumably not have arrived from directly above?" Bill Leatherbarrow- Director of the British Astronomical Association's Lunar Section.

It turns out that unless the angle of incidence is very low indeed the impact crater remains roughly circular.  Once the angle drops below 15 degrees, strange things start to happen to the crater's shape and more dramatically to the pattern of the ejecta rays. In such circumstances a butterfly shape of ejecta is formed - with ejecta being thrown out down range with a zone of avoidance up range from the point of impact and 'butterfly wings' extending out at 90 degrees to the line of travel of the impacting projectile.

The craters: Proclus, Stevinus A and Furnerius A, and Messier and Messier A, show the affects of impacts incident at low angles. In the case of the Messier twin craters they probably show the affects of a glancing blow from one projectile!

The  large crater Copernicus with ejecta rays radiating out more or less equally in all directions from the centre of the crater.  The enormous impactor that created Copernicus would have had an incident angle greater than 15 degrees.

Craters Stevinus A and Furnerius A with their butterfly ejecta ray patterns associated with low incidence impacts

Impacting asteroids coming in from the west at less than 15 degrees

Small craters Messier and Messier A - thought to have been created by one impactor coming in at a very low glancing angle from the east. The 'comet like tail' is the down range ejecta from the double impact.

Credits: Astronomy Now and Bill Leatherbarrow
All images taken from the Jodrell Plank Observatory.

" Each and every day, I like to discover something new and fascinating about the universe outside my own backyard!" Kurt Thrust Director the Jodrell Plank Observatory.