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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"

75 results found.

  1. EP250508a: Gemini NIR upper limits
  2. GRB 250322A: Gemini-South optical observations
  3. GRB 250210A: AstroSat CZTI detection
  4. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  5. IceCube Alert 241224.30: Global MASTER-Net observations report
  6. Fermi GRB 241118A: Global MASTER-Net observations report
  7. EP241107a: Gemini-South spectroscopic confirmation (z = 0.456)
  8. GRB241105A: Gemini-South Optical Afterglow Detection
  9. GRB 241030A: Swift/UVOT Detection
  10. EP241021a: Gemini-South detection of optical rebrightening
  11. GRB 230204B: Fermi GBM detection
  12. GRB 230204A: Swift/UVOT Upper Limits
  13. GRB 230102A: Fermi GBM Observation
  14. GRB221009A: Gemini-South Optical Afterglow Detection
  15. GRB 220715B: Swift/UVOT Upper Limits
  16. GRB 220608A: AstroSat CZTI detection
  17. GRB 220308B: Fermi GBM detection
  18. Fermi GRB 211211B: Global MASTER-Net observations report
  19. ZTF21aayokph (AT2021lfa): Redshift from Gemini South
  20. GRB 210104B: Swift/UVOT Upper Limits
  21. GRB 201223A: Swift/UVOT Detection
  22. Fermi GRB 201109A: Global MASTER-Net observations report
  23. GRB 201024A: Swift/UVOT Detection
  24. Fermi trigger No 607537834: Global MASTER-Net observations report
  25. LIGO/Virgo S200114f: Gemini Spectra of AT 2020vu, AT 2020vw, AT 2020vy, and AT 2020vz
  26. Swift GRB191226.25: Global MASTER-Net observations report
  27. GRB 191201A: AstroSat CZTI detection
  28. GRB190604B: Swift/UVOT detection
  29. GRB 181228A: Swift/UVOT Upper Limits
  30. GRB 180602A: Swift/UVOT Upper Limits
  31. GRB 171102B: Nanshan 0.36m and 0.60m optical upper limits
  32. GRB 170311A: Swift/UVOT Upper Limits
  33. GRB 160824A: Swift/UVOT Possible Afterglow Detection
  34. GRB 151031A: Swift/UVOT Detection
  35. GRB 151027A: UVOT Observations
  36. GRB 151023A: Swift/UVOT Upper Limits
  37. GRB 150710A: Swift/UVOT Upper Limits
  38. Swift Trigger 646423 is GS 1354-645
  39. GRB 140614A: Swift/UVOT Upper Limits
  40. GRB 140206A: Swift/UVOT Detection
  41. GRB 131127A: Swift/UVOT Upper Limits
  42. GRB 131002A: Swift/UVOT Detection
  43. GRB 130925A: Swift/UVOT Upper Limits
  44. GRB 130702A: P200 Spectroscopic Confirmation of Associated Supernova
  45. GRB 130515A: Swift/UVOT Upper Limits
  46. GRB 121123A: Swift/UVOT Observations
  47. GRB 120521C: Swift/UVOT Upper Limits
  48. GRB 111215A: Swift/UVOT Upper Limits
  49. GRB 111109A: Swift-BAT refined analysis
  50. GRB 110709B: Preliminary Swift-BAT refined analysis
  51. Swift/UVOT observations of GRB110520A
  52. Swift/UVOT observations of GRB110223b
  53. GRB 100606A: Enhanced Swift-XRT position
  54. INTEGRAL Alert n. 5995: MASTER-Net optical observations
  55. GRB 100302A: Swift/UVOT Upper Limits
  56. GRB090418A Rc-band photometry
  57. GRB 080919: Swift/UVOT Refined Analysis
  58. GRB 080916C: Swift UVOT Refined Analysis
  59. GRB 071117: Gemini Observations
  60. GRB 070419A, deep LBT photometry and possible supernova detection
  61. GRB070420: Swift UVOT continuing observations
  62. GRB061222A Swift/UVOT: Upper Limits
  63. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  64. GRB061002: Swift UVOT followup observations
  65. GRB 060807: UVOT Upper limits
  66. GRB 060510A: Swift/UVOT Detection of an Optical Afterglow
  67. GRB000418, HST/STIS Observations
  68. GRB 000418: Detection of the Host Galaxy
  69. The redshift of GRB 000418
  70. GRB000418, Radio detection
  71. GRB000418, K'-band photometry
  72. GRB 000418, Optical Observation
  73. GRB 000418, optical observation
  74. GRB 000418, Optical Observation
  75. GRB 000418, Optical Observation

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