SLOAN filter specifications for ULTRACAM, ordered in conjunction
with the ING (Vik Dhillon, 12/12/2000)
| Filter | CWL | FWHM |
| | (A) | (A) |
| u' | 3560+/-36 | 600+/-30 | 4500A+blocker |
| g' | 4825+/-48 | 1380+/-69 | cut-off at 5500A |
| r' | 6261+/-63 | 1382+/-69 | cut-off at 7000A |
| i' | 7672+/-77 | 1535+/-77 | cut-off at 8500A |
| z' | 9097+/-91 | 1370+/-69 |
- Central Wavelength (CWL) and Full Width Half-Maximum (FWHM)
specified in Angstroms.
- CWL specified to 1% at 0 degress C.
- FWHM specified to 5% at 0 degrees C.
- Circular filters of diameter 35mm.
- Filters to work in f/2.3 beam of ULTRACAM cameras.
- r', i' and z' are single substrates, u' and g' are composites
(to be confirmed).
- Filter thickness 5mm+-0.5mm (for both single and composite
substrate filters).
- All filters AR coated on both sides.
- Peak transmission should exceed 80% except for u' where the
peak transmission should exceed 70%.
- Blocking should be 1 part in 10000 in visual 300nm to 1200nm.
- Flatness lamda/2 per 20mm.
Some additional specifications for the filters from the Barr
Associates (www.barrassociates.com/datasheets/set3.html)
web-site (to be confirmed):
- Refractory oxide durable surface coating.
- Parallelism: 30 arcseconds.
- S/D: 60/40
- Construction:
u' - 3mm fused silica (+ coating) + 1mm UG-11 + 1mm S-8612 (+ coating)
g' - 3mm GG-400 (+ coating) + 2mm S-8612 (+ coating)
r' - 5mm OG-550 (+ coating)
i' - 5mm RG-695 (+ coating)
z' - 5mm RG-830 (+ coating)
Here are the tranmission curves given by Barr:
Here are the tranmission curves given by the ING (compared with the
UBVRIZ filter set used on the INT WFC):
