The "Pi of the Sky" apparatus continuously monitors the HETE FOV.
10 s exposures of a 33ox 33o field are taken by two cameras.
Twice a night the whole sky is scanned
(17 fields x 2 cameras x 2 exposures x 10s = 20min).
Targets of GCN alerts are also followed automatically.
Limiting magnitude for single images is 10-11m, whereas for 20 coadded images is 12-13m (depending on the Moon phase, etc.)
Statistics of "Pi of the Sky" observations
| 89 GRB observed by satellites from 2004.07.01 | ||||||
| apparatus off | North hemisphere | daytime | below horizon |
clouds | outside FOV | inside FOV |
| 1 | 18 | 40 | 8 | 4 | 16 | 2 |
| Gamma / X-ray satellite observations | Optical "Pi of the Sky" observations | |||||||
| GRB / XRF | UT | RA Dec | error | alert | before GRB | during GRB | after GRB | GCN |
| G 05 08 07 | 10:58:45 | 20h18m36 -32°34' | 50' | HETE | daytime | |||
| G 05 08 03 | 19:14:01 | 23h22m36 +05°48' | 4' | Swift | daytime | |||
| G 05 08 02 | 10:08:02 | 14h37m06 +27°47' | 3' | Swift | < horizon | |||
| G 05 08 01 | 18:28:02 | 13h36m33 -21°57' | 4' | Swift | daytime | |||
| G 05 07 30 | 19:58:23 | 14h08m17 -03°46' | 4' | Swift | daytime | |||
| G 05 07 26 | 05:00:17 | 13h20m12 -32°04' | 4' | Swift | outside FOV | |||
| G 05 07 24 | 12:34:09 | 16h24m51 -27°31' | 4' | Swift | daytime | |||
| G 05 07 21 | 04:29:14 | 16h53m47 -28°23' | 4' | Swift | clouds | |||
| G 05 07 17 | 10:30:52 | 14h17m20 -50°32' | 4' | Swift | < horizon | |||
| G 05 07 16 | 12:36:04 | 22h34m23 +38°42' | 4' | Swift | daytime | |||
| G 05 07 15 | 22:30:26 | 10h22m41 -00°04' | 4' | Swift | daytime | |||
| G 05 07 14B | 22:40:32 | 11h18m47 -15°32' | 4' | Swift | daytime | |||
| G 05 07 14 | 00:05:56 | 43h35m11 +69°08' | 2' | Integral | North hemisphere | |||
| G 05 07 13B | 12:07:18 | 20h31m16 +60°57' | 4' | Swift | North hemisphere | |||
| G 05 07 13 | 04:29:02 | 21h22m09 +77°04' | 4' | Swift | North hemisphere | |||
| G 05 07 12 | 13:58:40 | 05h10m48 +64°55' | 4' | Swift | North hemisphere | |||
| G 05 07 09 | 22:36:37 | 23h01m30 -38°58' | 3' | HETE | daytime | |||
| G 05 07 01 | 11:42:59 | 15h09m09 -59°25' | 3' | Swift | daytime | |||
| G 05 06 26 | 03:46:24 | 12h26m59 -63°08' | 2' | Integral | In the glow of Acrux | |||
| G 05 06 07 | 06:29:05 | 20h00m40 +09°08' | 4' | Swift | outside FOV | >60s: >12.5m | 3526 | |
| G 05 06 03 | 06:29:05 | 2h39m55 -25°11' | 4' | Swift | < horizon | |||
| G 05 05 28 | 04:06:45 | 23h34m07 +45°57' | 4' | Swift | North hemisphere | |||
| G 05 05 25 | 00:02:53 | 18h32m33 +26°20' | 3' | Swift | < horizon | |||
| G 05 05 22 | 06:00:36 | 13h20m37 +24°47' | 3' | Integral | outside FOV | >+75s: >11m | ||
| G 05 05 20 | 00:06:03 | 12h50m07 +30°27' | 3' | Integral | clouds | |||
| X 05 05 09C | 22:45:54 | 12h53m08 -44°51' | 10' | Swift | outside FOV | >+28min: >13m | ||
| G 05 05 09B | 04:00:19 | 12h36m13 +29°00' | 4' | Swift | outside FOV | |||
| G 05 05 09 | 01:46:29 | 20h42m21 +54°04' | 4' | Swift | North hemisphere | |||
| G 05 05 07 | 22:43:19 | 03h12m13 -11°04' | 4' | Swift | near horizon + clouds | |||
| G 05 05 05 | 23:22:21 | 09h27m08 +30°15' | 4' | Swift | clouds | |||
| G 05 05 04 | 08:00:59 | 13h24m01 +40°40' | 3' | Integral | clouds | |||
| G 05 05 02B | 09:25:41 | 09h30m10 +17°00' | 4' | Swift | < horizon | |||
| G 05 05 02 | 02:14:18 | 13h29m46 +42°40' | 3' | Integral | outside FOV | |||
| G 05 04 22 | 07:54:29 | 21h37m55 +55°47' | 4' | Swift | North hemisphere | |||
| G 05 04 21 | 04:11:52 | 20h28m58 +73°40' | 4' | Swift | North hemisphere | |||
| G 05 04 18 | 11:00:16 | 02h57m22 -18°32' | 4' | Swift | daytime | |||
| G 05 04 16B | 22:35:54 | 08h55m25 +11°10' | 4' | Swift | daytime | |||
| G 05 04 16 | 11:04:44 | 12h33m55 +21°03' | 4' | Swift | daytime | |||
| G 05 04 12 | 05:44:03 | 12h04m29 -01°15' | 4' | Swift | >11.5m | >11.0m | >11.5m | 3240 |
| G 05 04 10 | 12:14:25 | 05h58m59 +79°36' | 4' | Swift | North hemisphere | |||
| G 05 04 08 | 16:22:51 | 12h02m17 +10°51' | 1' | HETE | daytime | |||
| G 05 04 06 | 15:58:48 | 02h17m43 -50°11' | 4' | Swift | daytime | |||
| G 05 04 01 | 14:20:15 | 16h31m29 +02°11' | 6' | Swift | daytime | |||
| G 05 03 26 | 09:53:56 | 0h27m26 -71°22' | 3' | Swift | <-33min: >11m | outside FOV | 3146 | |
| G 05 03 19 | 09:31:19 | 10h16m38 +43°34' | 4' | Swift | North hemisphere | |||
| G 05 03 18 | 15:44:37 | 03h18m43 -46°24' | 4' | Swift | daytime | |||
| G 05 03 15 | 20:59:43 | 20h25m53 -42°35' | 4' | Swift | daytime | |||
| G 05 03 06 | 03:33:12 | 18h49m17 -9°10' | 4' | Swift | clouds | |||
| G 05 02 23 | 03:09:06 | 18h05m32 -62°30' | 4' | Swift | outside FOV | |||
| G 05 02 19B | 21:05:51 | 5h25m15 -57°45' | 4' | Swift | <-20.5h: >12m | daytime | >+3.7h: >10m | |
| G 05 02 19 | 12:40:01 | 11h05m43 -40°41' | 4' | Swift | <-3.7h: >11.5m | daytime | ||
| G 05 02 15B | 02:33:43 | 11h37m45 +40°48' | 4' | Swift | < horizon | |||
| G 05 02 15 | 02:15:29 | 23h13m35 +49°19' | 4' | Swift | North hemisphere | |||
| G 05 02 09 | 01:31:41 | 8h26m09 +19°41' | 7' | HETE | outside FOV | |||
| G 05 02 02 | 03:35:15 | 19h22m14 -38°43' | 3' | Swift | < horizon | |||
| G 05 01 29 | 20:03:03 | 16h51m12 -3°05' | 3' | Integral | daytime | |||
| G 05 01 28 | 04:19:54 | 14h38m18 -34°46' | 8" | Swift | <-19.7h: >11m | outside FOV | >+4.3h: >12m | |
| G 05 01 26 | 12:00:53 | 18h32m26 +42°22' | 0.5' | Swift | North hemisphere | |||
| G 05 01 24 | 11:30:03 | 12h51m31 +13°02' | 6' | Swift | daytime | |||
| G 05 01 23 | 10:22:54 | 10h31m34 -11°34' | 14' | HETE | <-1.8h: >12m | daytime | 2970 | |
| G 05 01 17B | 20:03:35 | 16h13m31 -70°21' | 10' | Swift | daytime | |||
| G 05 01 17 | 12:52:36 | 23h53m42 +65°56' | 4' | Swift | North hemisphere | |||
| G 04 12 28 | 10:49:13 | 22h26m34 +05°21' | 5' | Swift | daytime | |||
| G 04 12 26 | 20:34:19 | 05h18m10 +73°03' | 6' | Swift | North hemisphere | |||
| G 04 12 24 | 20:20:57 | 03h44m48 -06°39' | 7' | Swift | daytime | |||
| G 04 12 23 | 14:06:18 | 06h40m44 -37°04' | 7' | Swift | daytime | |||
| G 04 12 20 | 22:58:26 | 19h25m09 +60°37' | 12' | Swift | North hemisphere | |||
| G 04 12 19C | 20:30:33 | 22h55m52 -76°48' | 12' | Swift | daytime | |||
| G 04 12 19B | 15:38:48 | 11h10m42 -33°27' | 12' | Swift | daytime | |||
| G 04 12 19 | 01:42:55 | 0h24m26 +62°50' | 2.5' | Integral | North hemisphere | |||
| G 04 12 18 | 15:45:25 | 1h39m06 +71°20' | 2.5' | Integral | North hemisphere | |||
| G 04 12 17 | 07:28:30 | 10h59m10 -17°57' | 12' | Swift | outside FOV | >+30min: >11.5m | 2862 | |
| G 04 12 11 | 11:31:47 | 6h43m12 +20°24' | 2' | HETE | <-4.7h: >11m | daytime | ||
| G 04 10 16 | 04:39:39 | 1h44m44 -4°24' | 14' | HETE | outside FOV | |||
| G 04 10 15 | 11:12:21 | 0h18m37 +66°52' | 2.7' | Integral | North hemisphere | |||
| G 04 10 06 | 12:18:09 | 0h54m50 +1°14' | 5' | HETE | daytime | |||
| G 04 09 24 | 11:52:12 | 2h06m23 +16°07' | 6' | HETE | <-3h: >11m | daytime | ||
| X 04 09 16 | 00:03:30 | 23h01m30 -05°35' | 17' | HETE | <-13h: >12m | outside FOV | >+17min: >13m | 2725 |
| X 04 09 12 | 14:12:17 | 23h56m54 -01°00' | 7' | HETE | <-4.7h: >12m | daytime | >+19h: >10m | |
| X 04 09 03 | 18:18:10 | 18h03m22 -25°15' | 2'.5 | Integral | <-18h: >10m | daytime | ||
| G 04 08 27 | 11:51:11 | 15h16m59 -16°08' | 3' | Integral | daytime | >+12h: >10m | ||
| X 04 08 25B | 16:21:38 | 22h46m34 -02°24' | 9' | HETE | <-6.7h: >10m | daytime | >+17h: >10m | |
| G 04 08 25A | 03:30:30 | 22h58m59 -10°56' | 7' | HETE | <-11s: >10m | >10m | >+7s: >9.5m | 2677 |
| G 04 08 12 | 06:02:05 | 16h26m05 -44°43' | 2' | Integral | outside FOV | >+20min: >12m | ||
| G 04 08 10 | 14:15:36 | 23h54m08 -35°04' | 30' | HETE | daytime | |||
| G 04 08 02 | 18:02:21 | 18h47m24 -44°29' | 22'x330' | HETE | daytime | |||
| G 04 07 30 | 02:12:23 | 15h53m16 -56°27' | 2' | Integral | outside FOV | |||
| G 04 07 09 | 00:58:08 | 20h53m53 -28°13' | 95' | HETE | switched off | |||
| X 04 07 01 | 13:00:55 | 20h47m46 -40°14' | 8' | HETE | daytime | |||