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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

73 results found.

  1. EP260402a / GRB 260402A: Mephisto optical upper limits
  2. EP260403a: Mephisto optical upper limits
  3. GRB 260307B: Mephisto optical upper limits
  4. EP260227a: Mephisto optical detection
  5. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  6. EP260213a: Mephisto optical upper limits
  7. GRB 251222A: radio detection with the VLA
  8. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  9. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  10. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  11. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  12. GRB 250924A: 1.6m Mephisto optical upper limits
  13. EP250901a: Mondy, Assy and SAO RAS optical limits
  14. EP250901a: Mephisto optical upper limits
  15. GRB 250713A: Mephisto optical upper limits
  16. sb25061207: Mephisto optical upper limits
  17. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  18. GRB 250515A: 1.6m Mephisto optical detection
  19. EP250511a: Mephisto optical upper limits
  20. GRB 250506A: Mephisto optical upper limits
  21. GRB 250419A: Mephisto Multi-band Optical Detection
  22. EP250421a: Mephisto optical counterpart confirmation
  23. EP250404a: Mephisto multi-band optical detection
  24. GRB 250403A: 1.6m Mephisto multi-band optical detection
  25. GRB 250327B: Kilonova-Catcher Observations
  26. GRB 250329B: CAHA 2.2m telescope optical limit
  27. GRB 250328A: 1.6m Mephisto optical observations
  28. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  29. GRB 250327B: MASTER detection of OT rebrightening
  30. GRB 250327B: 1.6m Mephisto optical observations
  31. EP250308a: 1.6m Mephisto optical upper limits
  32. GRB 250226A: GRANDMA Optical Observations
  33. GRB 250226A: Fermi GBM Observation
  34. EP250226a/GRB 250226A: 1.6m Mephisto observations
  35. EP250223a: 1.6m Mephisto and 50cm array observations
  36. GRB 250221A: 1.6m Mephisto optical detection
  37. EP250220a: 1.6m Mephisto observations
  38. GRB 250219A: 1.6m Mephisto optical upper limits
  39. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  40. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  41. GRB 250109A / EP250109a: Mephisto optical upper limits
  42. EP250108a: Mephisto detection
  43. GRB 250103A: 1.6m Mephisto optical observations
  44. GRB 241228B: Fermi-LAT detection
  45. GRB 250101A: 1.6m Mephisto multi-band optical followup
  46. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  47. EP241217a: 1.6m Mephisto multi-band optical observations
  48. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  49. EP241201a: 1.6m Mephisto Optical Upper Limits
  50. EP241126a: 1.6m Mephisto Optical Upper Limits
  51. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  52. GRB 241112B: Mephisto further optical observations
  53. GRB 241115A: Mephisto upper limits
  54. GRB 241113B: Mephisto upper limits
  55. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  56. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  57. GRB 241112B: Mephisto optical upper limits
  58. EP241021a: Optical rebrightening observations with Mephisto
  59. GRB 241030A: Multiband optical detection with Mephisto
  60. GRB 241029A: GOTO optical afterglow detection
  61. GRB 241029A: Mephisto observations
  62. GRB 241018A/sb24101802: Mephisto optical upper limit
  63. GRB 241017A/sb24101702: Mephisto optical upper limit
  64. EP240913a/GRB 240913C: 1.6m Mephisto observations
  65. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  66. GRB 240828B: Mephisto optical upper limit
  67. GRB 240825A: MASTER optical counterpart observation
  68. GRB 240825A: 1.6m Mephisto multi-band detection
  69. GRB 240811A: Upper limits with Mephisto
  70. GRB 240805B: Optical detection with 1.6m Mephisto
  71. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  72. GRB231111A: MDM 2.4m Hiltner Telescope Observation
  73. GRB231111A: Optical follow-up observations with Mephisto

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