This page contains information on the weekly inspection of the WHT primary mirror.
Visual inspection of the primary mirror at WHT
|
Date |
Weather in past period? (rain, humidity, dust) |
Appearance of the primary |
Reflectivity |
Surface roughness RMS |
Action taken |
Comments |
Link to photo |
Inspector's name |
| 25 Feb 15 | High cloud and possible rain in previous 2 nights | Dusty all over with a few dozen water streaks crossing the dust vertically, mostly on lower half. No major exposure to rain. | - | - | none | To be measured and CO2 cleaned in the coming week. | Neil O'Mahony | |
| 8 Aug 14 | Calima followed high thick high cloud. | slight fog, similar to condensation, a pattern seen at high AoI from application of sponges during water wash. | - | - | none | To be measured and CO2 cleaned by 2 Sept. | Fog | Neil O'Mahony |
| 26 May 14 | Period of high humidity | Clean but with new drip marks, possibly there since wash in April | - | - | none | Drips | Neil O'Mahony | |
| 24 Feb 14 | Period of high humidity | Extensive water-borne dust stains, from rain and/or condensation | - | - | Program a water washing (10 April) | Water Stains | Neil O'Mahony | |
| 23 Aug 12 | New calima espisode. Observing stopped due to thick high cloud. | Same as on 01 Aug, slightly dustier. | - | - | To be cleaned with CO2 once weather stabilises. | Neil O'Mahony | ||
| 6 Aug 12 | Calima, high cloud | No new rain spots since 2 Aug wash. Old spots discernible. Long water drip marks under Nasmyth baffle. | - | - | None |
20120802 Far side washed, near side with rain spots |
Neil O'Mahony | |
| 14 Mar 12 | calima and high cloud | A light covering of small spots caused by rain containing calima dust. Also larger dribble marks (photo). | 85.0% | 49 | Cleaned with CO2. Measurement afterwards. | 1 and 2 Water dribble marks | Neil O'Mahony | |
| 2 Feb 12 | N/A Straight from Alum tank |
Crescent shaped area ~1m wide in lower part (from AP3), half radius distance, where fresh aluminium appears different shade. Half a dozen Al 'drops'. No sign of Feb 2011 tool damage. | 89.7% (IRIS) | - | None | Shaded area attributed to cleaning marks. Reflectivity here (GTC IRIS) only 0.5% less. Scattering also lower. | Neil O'Mahony, Juerg Rey | |
| 26 Sept 11 | Fault 19867 Rain on 22/9 |
A light covering of small spots caused by rain containing calima dust. | 82.2% | 81 | Will clean with CO2 ASAP | Neil O'Mahony | ||
| 17 Feb 11 | Fault 19511 | Spotted, despite washing 1 month previously. 3 small damage marks at 3 o'clock (AP3) ~30cm from edge. Microscope lens inspection suggests coating damage, metal deposits. Longer, shallow scratches in same area. | 83.4% | 66 | none | Possible substrate damage cannot be determined. Has not influenced decision to forego aluminization this year. | anotated photo | Neil O'Mahony |
| 26 Feb 08 | high clouds, high humidity | The spots and the stains are there. There are new stains on the right side (AP3) | 83.0% | 76.610 | CO2 cleaning | All the reflectivity, scattering and surface roughness have been improved | Tibor Agocs | |
| 13 Feb 08 | high clouds, high humidity | The spots and the stains are there. Apart from it the mirror is in a good state. | 83.8% | 77.375 | none | CO2 cleaning is necessary (today the humidity was too high) | Tibor Agocs | |
| 29 Oct 07 | high clouds, high humidity, calima | The spots and the stains are there. Apart from it the mirror is in a good state. | 86.7% | 49.140 | none | The results are almost the same as from the last measurements after the CO2 cleaning. | Tibor Agocs | |
| 04 Oct 07 | high clouds, high humidity, calima | The spots and the stains are there. | 84.1% | 61.996 | CO2 cleaning | All the reflectivity, scattering and surface roughness have been improved | Tibor Agocs & Neil O'Mahony | |
| 24 July 07 | Strong calima last week | The spots and the stains are there. Surface visibly dustier than in previous inspection. | 87% | 57.159 | CO2 cleaning | Surface dust noticeably improved, reflectivity too. | Tibor Agocs & Neil O'Mahony | |
| 22 May 07 | high clouds, rain, humidity, petals were left open on the 21th of May | The spots and the stains are there | 87.2% | 44.0 | none | The reflectivity and the surface roughness is still good in contempt of the spots | see below | Tibor Agocs |
| 24 April 07 | high clouds, humidity | The spots and the stains are there (see image) | 87.3% | 36.6 | none | The reflectivity and the surface roughness is really good in contempt of the spots | spots | Tibor Agocs |
| 13 April 07 | All kinds: dust, rain, high cloud, humidity | Large water/dust spots all
over. No water streaks. Small opaque stains at 9 o'clock, 30-50 cm from the baffle. Looks like dirt falling from small distance (no splash). |
N/A | N/A | CO2 cleaning after inspection | Condensation or possibly light rain. 1 month since last inspection. | photo4 | Neil O'Mahony |
| 13 March 07 | humidity high on some days | Clean. Two small drops (5-10 mm) at 6 o'clock | N/A | N/A | none | It seemed as some kind of liquid dropped down to the mirror | photo3 | Tibor Agocs |
| 28 Feb 07 | humidity high on Sat and Sun during the day | Clean. The spots are still there. | N/A | N/A | none | The spots are probably because of the aluminising. | photo2 | Tibor Agocs |
|
21 Feb 07 |
humidity (1/2 night) | Clean. 3 or 4 black spots < 5mm | N/A | N/A | Blowing, did not remove spot | Oil? Too small to concern. | photo1 | Neil O'Mahony |