Melbourne Telescope Research Articles

The Great Melbourne Telescope

The Great Melbourne Telescope

Book Review: The Great Melbourne Telescope, the Great Melbourne Telescope

THE GREAT MELBOURNE TELESCOPE The Great Melbourne Telescope. Richard Gillespie (Museum Victoria Publishing, Melbourne, 201 1). Pp. 188. AUD 29.95 (paperback). ISBN 978-1-92183-305-2.This readable and well-illustrated book takes a journey that begins in 1840s Ireland and passes through the astronomical elites of Victorian Britain, colonial Australian society and twentieth-century international collaborative research programmes. The telescope that provides the focus of this story is both a remarkable physical presence and an object of different meanings in the minds of those who dreamed it up, designed it, built it, worked with it or simply visited it. The cast of characters who swiftly cross these pages include British princes, a Fenian agitator, colonial officials and, of course, astronomers major and minor.Gillespie commendably handles this broad canvas and the specific or more technical details. The content, bibliography and endnotes are proof of knowledge and research that is woven well into an engaging narrative, only occasionally weighted down with the detail necessary to explain the frequent delays and pauses that characterized the history of this telescope. Each chapter opens with a section of semi-dramatized storytelling that, although it felt a little artificial with repetition, works to keep the reader's interest and, more importantly, to focus attention on telling episodes.Thus the first chapter opens on a cold night in Ireland, with Lord Rosse, Sir James South and Thomas Romney Robinson observing with Rosse's 'Leviathan'. These men, the ambitious telescope and the aim of resolving disputes about the nature of nebulae form the story's background. The southern hemisphere beckoned as a field that, despite John Herschel's work, remained relatively unexplored, and with climates more promising than Ireland's for the use of large mirrored telescopes. Rosse and Robinson, while President of the Royal Society and the British Association for the Advancement of Science respectively, had their moment in 1852 to create the joint Southern Telescope Committee.The published correspondence of this committee presents the historian with a wonderful resource to explore the currents of astronomical research, telescope design, politics and personalities. Disagreements caused delay as did, almost fatally to the project, the Crimean War. It took intense lobbying from the colonies to revive the project, and so enters, in the second chapter, the bounding figure of William Wilson, an ambitious, undiplomatic professor of mathematics in Melbourne. Gillespie's account of society in colonial Victoria is particularly well drawn, with a sense of its burgeoning development until depression hit late in the century. It is a place where names and fortunes could be made, where local, colonial and national identities were consciously developed, and where a large telescope could make a big statement. …

Photometric Confirmation of MACHO Large Magellanic Cloud Microlensing Events

We present previously unpublished photometry of three Large Magellanic Cloud (LMC) microlensing events and show that the new photometry confirms the microlensing interpretation of these events. These events were discovered by the MACHO Project alert system and were also recovered by the analysis of the 5.7 year MACHO data set. This new photometry provides a substantial increase in the signal-to-noise ratio over the previously published photometry and in all three cases, the gravitational microlensing interpretation of these events is strengthened. The new data consist of MACHO-Global Microlensing Alert Network (GMAN) follow-up images from the CTIO 0.9 telescope plus difference imaging photometry of the original MACHO data from the 1.3m Great Melbourne telescope at Mt. Stromlo. We also combine microlensing light curve fitting with photometry from high resolution HST images of the source stars to provide further confirmation of these events and to show that the microlensing interpretation of event MACHO-LMC-23 is questionable. Finally, we compare our results with the analysis of Belokurov, Evans & Le Du who have attempted to classify candidate microlensing events with a neural network method, and we find that their results are contradicted by the new data and more powerful light curve fitting analysis for each of the four events considered in this paper. The failure of the Belokurov, Evans & Le Du method is likely to be due to their use of a set of insensitive statistics to feed their neural networks.

THE TELESCOPE SYSTEM OF THE MACHO PROGRAM

ABSTRACT The renovation of the Great Melbourne Telescope for use as a 1.27m aperture telescope in the MACHO program is described. The current mode of telescope structure, drive systems and control are outlined and ongoing programs of dome seeing improvement are discussed.

A Dual CCD Mosaic Camera System Searching for Massive Compact Halo Objects (Machos)

The Macho Collaboration uses a dedicated 1.27-m telescope (The Great Melbourne Telescope) at Mount Stromlo to make photometric measurements of tens of millions of stars per night searching for the gravitational microlensing signature of MACHOs in the halo and disk of the Milky Way. A prime focus corrector and dichroic beamsplitter provide red (6300–7800 å) and blue (4500–6300 å) foci with one degree fields. A two by two mosaic of 2048 × 2048 pixel CCDs in each focal plane provides simultaneous images of 0.5 square degrees. By August of 1994, more than 20,000, 32 megapixel images will have been collected of fields in the Large Magellanic Cloud (LMC), Small Magellanic Cloud and the bulge of the Milky Way. We have implemented an online analysis system which produces photometric reductions of a night's data (five Gbyte of images) within 24 hours. This system allows us to identify and follow interesting events in real-time. In this search, we have identified more than 60,000 variable stars, and a preliminary analysis of their types and distribution will be presented. Microlensing events toward the LMC and the bulge have been discovered and detection efficiencies are being calculated to constrain the MACHO content of the Milky Way's halo.

A Dual CCD Mosaic Camera System Searching for Massive Compact Halo Objects (Machos)

The Macho Collaboration uses a dedicated 1.27-m telescope (The Great Melbourne Telescope) at Mount Stromlo to make photometric measurements of tens of millions of stars per night searching for the gravitational microlensing signature of MACHOs in the halo and disk of the Milky Way. A prime focus corrector and dichroic beamsplitter provide red (6300–7800 å) and blue (4500–6300 å) foci with one degree fields. A two by two mosaic of 2048 × 2048 pixel CCDs in each focal plane provides simultaneous images of 0.5 square degrees. By August of 1994, more than 20,000, 32 Megapixel images will have been collected of fields in the Large Magellanic Cloud (LMC), Small Magellanic Cloud and the bulge of the Milky Way. We have implemented an online analysis system which produces photometric reductions of a night's data (five Gbyte of images) within 24 hours. This system allows us to identify and follow interesting events in real-time. In this search, we have identified more than 60,000 variable stars, and a preliminary analysis of their types and distribution will be presented. Microlensing events toward the LMC and the bulge have been discovered and detection efficiencies are being calculated to constrain the MACHO content of the Milky Way's halo.

The Great Melbourne Telescope and Other 19th Century Reflectors.

Historical Records of Australian Science publishes peer-reviewed articles and book reviews on the history of science and scientists in Australia and the southwest Pacific, biographical memoirs of deceased Fellows of the Academy, and an annual bibliography of the history of Australian science

The calamity of the Great Melbourne Telescope

The calamity of the Great Melbourne Telescope

The calamity of the Great Melbourne Telescope

The calamity of the Great Melbourne Telescope

The Calamity of the Great Melbourne Telescope

Sir William Herschel and his sister, Caroline, had swept the skies over England as members of the court of George III. They had made amazing discoveries: a new planet in our solar system, the movement of the solar system with respect to the fixed stars, and hundreds of new nebulae and star clusters.Then Sir William’s son John swept the southern skies from Cape Town, South Africa (1834 to 1838), mapping and sketching many more stars and nebulae.

News and Views

VERY hearty congratulations are extended to Sir Howard Grubb, who celebrates his eighty-sixth birthday on Monday next, having been born on July 28, 1844. Sir Howard was educated privately and at Trinity College, Dublin. In most parts of the world where observatories exist one may be sure that he has had a leading and expert part in the preparation of their equipment of mirrors, objectives, and all the varied apparatus and machinery of the modern astronomical observatory. Particularly is this the case as regards many of the great astronomical observatories of America; here his resourceful ingenuity has long been acclaimed. He has published many memoirs, chiefly through the medium of the Royal Dublin Society—among the earliest, “The Great Melbourne Telescope” (1870) and “On Clocks for Equatorial Telescopes” (1875). In 1896 he read a paper at the Royal Institution on “The Development of the Astronomical Telescope”. In 1881 Sir Howard was the recipient of the Cunningham gold medal of the Royal Irish Academy, in recognition of work in the service of astronomers; in 1912 he received the Boyle medal of the Royal Dublin Society, awarded for scientific labours of outstanding merit carried out by Irishmen or in Ireland. Holding the honorary degree of master of engineering in the University of Dublin, Sir Howard is also an honorary member of the Institution of Civil Engineers of Ireland. He was elected into the fellowship of the Royal Society of London so long ago as 1883.

VIII. Some observations on the amount of light reflected and transmitted by certain kinds of glass

Although for both theoretical and practical purposes it is important to know the amount of light reflected from the surface of glass, and the loss which light suffers in passing through glass, but few accurate experiments appear to have been made on this subject. Dr. Robinson, in the report on the Melbourne telescope (‘Phil. Trans.,’ 1869, p. 127), gives an account of experiments made by Lord Rosse, Mr. Grubb, and himself to determine the amount of light transmitted by telescopic object glasses, and through various kinds of flint and crown glass; he states that Lord Rosse’s and Mr. Grubb’s experiments were made with a Bunsen’s photometer, and his own with a Zollner’s photometer. Dr. Robinson assumed the truth of Fresnel’s formulæ, and then calculated the values of the extinction coefficients ϵ- nt from the expression n = (log ρ 2 — log I )/( t X modulus), where I is the intensity of the emergent light, t the thickness of the glass, and ρ 2 the coefficient giving the amount which escapes reflection at the two surfaces.

The Melbourne Telescope

MR. ELLERY has been so good as to send me an enlargement of the lunar photograph taken with the great Melbourne telescope, to which you allude at p. 228, No. 142 of your Journal. This picture, Mr. Ellery tells me, was taken on the second evening of trial; it is very beautiful, although not so critically sharp as several I have obtained with my Newtonian equatorial of 13 in. aperture, and a little more than 10 ft. focal length. This sharpness, however, is a mere question of the shadiness of the atmosphere; and I feel persuaded that pictures will be taken with the Melbourne telescope far surpassing any hitherto procured. In my telescope the focal image varies from I in. to 12/10 in. in diameter, according to the distance of the moon from the earth. The primary picture of the Melbourne telescope (an enlargement of which has been sent to me) is 3 3/16 in. in diameter; hence the structure of the collodion and minute defects in it are of much less importance than when smaller instruments are used.

XVII. Observations with the great melbourne telescope, in a letter to Prof. Stokes

Dear Sir,—I have little more definite to tell you with reference to the star η Argûs; thinking that a larger dispersion would be of advantage, I have had a supplementary arrangement added to the spectroscope, by means of which a direct prism may be interposed between the collimator and the usual prism.

Science in Victoria

ONE or two interesting subjects were discussed at a recent meeting of the Royal Society of Victoria, and we are favoured by a correspondent with the following particulars:—Notes on the working of the great Melbourne telescope, which some time ago was inconsiderately pronounced to be a failure, which were read by Mr. Farie MacGeorge, who has had charge of the instrument since Mr. Le Sueur left. It was stated that the speculum polished by Mr. Le Sueur had worked very satisfactorily, and some fresh discoveries with regard to Sirius and the star d were thus described by Mr. MacGeorge:—“On 9th Dec. 1870—indifferent evening—I noted all the faint stars near Sirius for future identification. On the 18th jan. 1871, for the first time, I chanced upon Lassell's observations of Sirius in the ‘Memoirs of the Royal Astronomical Society,’ 1867. Mr. Martin there mentions having suddenly found a very faint star in the neighbourhood of Sirius which had, until then, escaped keen observers like Struve, Lassell, and himself, in the exquisite 4ft. equatorial at Malta. On comparing the position of this faint star—now called Lassell's Companion—with the faint stars noted by me on 9th December, it evidently corresponded with one noted on that date, so that with our great equatorial my eye, unbiassed by previous knowledge, detected at the first inspection on an indifferent evening an object which had long escaped these careful and experienced observers in the great Malta equatorial, an instrument of acknowledged excellence and equal aperture to our own. Several still fainter stars have since been seen near Sirius, two of them between Lassell's Companion, the star d, and Sirius. So far as I have yet seen, any want of definition is evidently due to atmospheric defects, not instrumental ones, the power of definition being at all times in direct ratio with the goodness of the evening.” Prof. Wilson made a suggestion to the society respecting an expedition to Cape York, in a steamer, to witness the Total Eclipse of the Sun on the 12th December next, the eclipse being visible along a portion of the northern coast of Australia. The proposal was favourably entertained, and an understanding arrived at that it should receive fuller consideration at the next meeting. The annual meeting of the Acclimatisation Society of Victoria was held on the 10th March, Dr. Black, the President, occupying the chair. In their customary report to the subscribers, the council, while regretting the smallness of their numbers, stated that under the management of the new secretary Mr. A. C. Le Sœur, the society bade fair to again become extensively useful. It was mentioned that four ostriches which had been received from South Africa had been taken charge of by Mr. Samuel Wilson, of Longerenong, and had now increased to sixteen, and there was every reason to suppose that their numbers would be considerably augmented in the course of this season. So far the experiment had been a marked success. Ostrich farming was a profitable occupation at the Cape colony, and it was hoped it would ultimately become so here. The climate of the Wimmera district, it was remarked, appeared to be well adapted to their habits; as a proof of which, the young Australian birds were now taller than the parent stock. It was stated, amongst other subjects dealt with in the report, that the society had done and was doing all in its power to encourage sericulture in the colony, and to this end had, in conjunction with Dr. Von Mueller, sent white mulberry cuttings and plants to all parts of Victoria. Some months ago a box of silkworm eggs was sent by the Governor of India to his Excellency the Governor, who kindly handed them to the society for distribution, and lately a supply of very superior Japanese eggs, such as were seldom sold to foreigners, had been forwarded by Dr. Bennett, the hon. secretary of the Acclimatisation Society of New South Wales. The Silk Supply Association of London, it was mentioned, in one of their reports recently published, recognised no less than 36,000 square miles of country in Victoria as well suited to the growth of silk; and when the numerous young plantations came into bearing a great stimulus would be given to this industry, which in all probability would, before many years, add materially to the wealth of the colony.

II. Spectroscopic observations of the nebula of Orion, and of Jupiter, made with the great Melbourne telescope

In one particular the spectroscopic observations of the nebula of Orion are not void of interest; they show distinctly that considerable nebulosity exists within and about the trapezium. The image at the slit is sufficiently large to well separate the stars of the trapezium, so that when two of these are* as it were, threaded on the slit, a clear space lies between them ; this in the spectroscope gives the well-known lines with little, if at all, less brilliancy than the general bright nebula. The small comparison-mirror being removed, the available slit is *4 inch high, equivalent in the case of the Cassegrain image to about 43" arc; with an image condensed about three times (which is the usual arrangement and still allows sufficient separation), the slit may, therefore, be made to considerably overlap the trapezium contour, and thereby, at the same time as the trapezium, light from the brightest part of the nebula is under in-: spection; it is curious to see that the spectral lines run with almost continuous brightness throughout the height of the slit.

II. Account of the great Melbourne telescope from April 1868 to its commencement of operations in Australia in 1869

A description of the great Melbourne reflector, and its history, up to the time of inspection by the Committee, have been communicated to the Royal Society; the following additional account of the doings connected therewith since the instrument was consigned to my care may be of interest to the Society. Mr. Grubb commenced taking down the telescope at the end of April 1868 ; this was accomplished in no great length of time, and without any difficulty. The specula (by the advice of Mr. Lassell, who had found this method answer perfectly) were coated over with shellac varnish to prevent oxidation on the voyage o u t; they were then protected in their cells and on their lever supports by strong double wood casings, and the other parts of the telescope and machinery cased or otherwise protected. To only casualty which there seemed to be any reason to fear .could give to any serious consequences was a tilting over of the speculum cases, their great weight was, perhaps, a sufficient guarantee from such an event§ it was nevertheless thought prudent that the telescope, and machinery genrally, should not be left entirely to the tender mercies of the shipping and crane labourers ; I was therefore present at the shipping in Dublin board a steam-tug hired for the purpose, and at the transshipment in Liverpool, on board the * Empress of the Seas.’

III. On the nebulæ of Argo and Orion, and on the spectrum of Jupiter

Among the following observations made with the great Melbourne telescope, the most important are those of η Argo; the spectrum of this star is crossed by bright lines . The mere fact of a bright-line spectrum is not very difficult to ascertain on a good night; for although from faintness of the light the phenomenon is necessarily delicate, yet the bright lines occasionally flash out so sharply that the character of the spectrum cannot be mistaken. The most mark lines I make out to he, if not coincident with, very near to C, D, b , f, and the principal, green nitrogen line. There are possibly other lines, but those mentioned are the only ones manageable.

Societies and Academies

LONDONRoyal Society, March 3.—The following papers were read:-“Results of the Monthly Observations of Dip and Horizontal Force, made at the Kew Observatory, from April 1863 to March 1869 inclusive.” By Dr. Balfour Stewart. “Spectroscopic observations on stars and nebulse made with the Great Melbourne Telescope.” By A. Le Sueur. “On the nebula of Argo, and on the spectrum of Jupiter.” By A. Le Sueur. We shall return to these papers next week.

Societies and Academies

Societies and Academies