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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"

71 results found.

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

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