Cleaning the optics of SPIRIT telescopes requires a great deal of care. The surfaces of primary mirrors in particular are extremely delicate, and can be damaged using conventional cleaning techniques. Telescope optics should never be touched, though traditional surface cleaning techniques usually include surface contact. Washing mirrors introduces other problems such as streaking and can be difficult to undertake with telescope optics in situ. Moisture ingress at the edge of primary mirrors can also affect coatings over time.
The annual SPIRIT mirror cleaning routine includes the application of a polymer solution called First Contact that absorbs surface dust and debris. It dries as a flexible film that has minimal surface adhesion so that it can be safely removed without affecting delicate surface coatings.
The SPIRIT II primary mirror before cleaning:
Application of First Contact polymer solution:
Removing the cured ‘film’:
A clean SPIRIT II primary mirror:
It is often said that there is no ‘up’ in space. However, astronomers still need to orient themselves with the night sky in order to measure and explain the objects they observe. This short guide will explain the orientation of images taken with SPIRIT telescopes.
This time lapse movie shows automated operation of SPIRIT I from pre-dusk until dawn, condensed into a two minute sequence. The movie shows the telescope following a set of a dozen minor planets from east to west, imaging them repeatedly over the course of the entire night.
Giants in the sky
February 2014 is dominated by two celestial giants – the great nebula in Orion (M 42) and the planet Jupiter.
The constellation of Orion the hunter features prominently in the sky for much of February. Its well known and often targeted nebula (M 42) is easily imaged by SPIRIT with exposures less than 60 seconds. A more challenging target is the Horsehead nebula (IC 434). It is best imaged when near or just past the meridian using the H-a filter on SPIRIT I and exposures upwards of 60 seconds.
In the south, the large Magellanic cloud – one of the Milky Way’s satellite galaxies – features strongly. A naked eye object under rural skies, the “LMC” contains an endless variety of interesting clusters and nebulae, including the bright Tarantula nebula (NGC 2070). Later in the evening, and as the month progresses, the Eta Carina region will follow the LMC across the southern sky and is similarly rich in nebulae and clusters including the area in and around NGC 3372.
Although low in the northern sky, Jupiter, the largest planet in our solar system, can be imaged using filtered exposures of less than half a second. Jupiter’s four Galilean satellites appear easily within the field of either of the SPIRIT telescopes, and if imaged over several nights will show changing positions as they orbit the giant planet. Once imaged, the moons can be easily identified using planetarium software such as Stellarium.
For those interested in something different, a number of very bright open clusters are rising during February. These include M 93, M 46 and M 47. These interesting and extended clusters are best imaged with the wide field of SPIRIT II, and exposures of 30 seconds or less.
The moon is full on February 15th, so the best times to image faint objects will fall within the first week, or during the last week of the month.
The Perth night sky facing south at 8:00 pm on February 15th
(click on image to enlarge)
The SPIRIT guides and documents web page has been updated. A number of new items have been added, including a revised LRGB Photoshop guide, and additional material on FITS file conversion. An exposure guide has also been added to assist new users with target planning.
As always, the guides and documents web page provides a ‘one stop shop’ for all SPIRIT information.
The page can be accessed here.
Author and astronomer Ron Wodaski has generously provided his book The New Astro Zone System for Astro Imaging free to teachers and students using SPIRIT.
The ‘Zone System’ provides invaluable information for getting the most out of your astro images using Adobe Photoshop, and is particularly useful to teachers and students who have attended the SPIRIT 103 workshop at SPICE.
Authorised teachers and students can download a PDF copy of the book here.
A password to unlock the file can be obtained by contacting us.
Additional support materials and tutorial images can be downloaded free from the Tzec Maun web site.
A new student activity on variable stars is being developed. A hands on workshop will provide information on how to undertake photometric observations of short period variable stars using the SPIRIT telescopes, and then create light curves that can complement existing published data.
A half day student workshop for advanced SPIRIT users will be offered later this year. Anyone interested in participating in pilot activities should contact us.
Of Galaxies and Globulars
With the centre of the milky way now well past the meridian at sunset, it’s time to start looking beyond the bright nebulae and clusters that dominated the skies from July to September.
Rising in the east is the magnificent Sculptor galaxy, NGC 253. One of the largest and brightest galaxies in our skies, it fills the field of view of both SPIRIT I and SPIRIT II (check out this image of NGC 253 taken by SPIRIT I in 2011). NGC 253 is one of our closest neighbours in the local group of galaxies and shows areas of intense star formation in its near edge-on spiral arms. October is a great month to plan some long exposures of NGC 253, as it is directly over head at about 10:30pm at mid month. Close to NGC 253 are a number of other galaxies worth targeting, including NGC 247, NGC 55 and the beautiful face on spiral galaxy NGC 300. Longer exposures of up to a minute or more under good sky conditions are required to reveal the detail in these targets.
Meanwhile, high in the south east is the impressive globular cluster NGC 104, better known as 47 Tucanae. It too crosses the meridian mid month at about 10:30pm. The second largest globular cluster in the sky (after Omega Centauri), 47 Tucanae and its nearby smaller companion NGC 362 are located close to another member of our local group of galaxies, the Small Magellanic Cloud.
47 Tucanae is uniquely placed in the southern sky and is the envy of all northern hemisphere observers. Imaging this object is a must for all users of SPIRIT, and relatively short exposures (less than 30 seconds) through the red, green and blue filters can be used to successfully create impressive colour images of this interesting globular cluster.
The Perth night sky facing south at 7:30 pm on October 15th
(click on image to enlarge)
A Stellar Cemetery
September presents the best time of the year to image two famous northern hemisphere objects; the Dumbbell Nebula (M27) and the Ring Nebula (M57).
The Dumbbell Nebula is the first and perhaps most famous planetary nebula discovered. The remnant of a sun-like star having exhausted its hydrogen fuel, the dumbbell shape shows the expanding shell of gas ejected by a star after becoming a red giant. The ring nebula also shows an expanding shell of gas around a small white dwarf star.
These two planetary nebulae bare no association with planets. They are the remnants of stars that provide an insight into what lays in store for our sun when it eventually reaches the end of its life.
Both objects are low in the northern sky. Use Stellarium to plan your timing to capture them at their highest points, as they cross the meridian. The objects can only be reached using SPIRIT II.
A bright spiral in Pavo
High overhead mid month is the beautiful spiral galaxy NGC 6744. An easy target for either SPIRIT I or SPIRIT II captured with exposures of around 60 seconds.
Last chance to image the Trifid
With the centre of the Milky Way now heading westwards, September is a good month to image the bright Sagittarius nebulae as they are now well past the Perth city glow. The famous quartet includes: M16 (The Eagle Nebula), M17 (The Omega Nebula), M8 (The Lagoon Nebula) and M20 (The Trifid Nebula). A host of globular clusters also lay close to this rich area of the milky way sky.
The moon is full on September 30th, so the best times to image faint objects will be between September 8th and September 23rd.
The Perth night facing south at 7:30 pm on September 15th
(click on image to enlarge)