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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"

84 results found.

  1. EP250508a: Gemini NIR upper limits
  2. GRB 250322A: Gemini-South optical observations
  3. Fermi trigger No 763933627: Global MASTER-Net observations report
  4. EP250225a: Global MASTER-Net observations report
  5. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  6. Integral GRB241215.58: Global MASTER-Net observations report
  7. GRB 241212A: AstroSat CZTI detection
  8. Fermi trigger No 754701230: Global MASTER-Net observations report
  9. EP241107a: Gemini-South spectroscopic confirmation (z = 0.456)
  10. GRB241105A: Gemini-South Optical Afterglow Detection
  11. EP241021a: Gemini-South detection of optical rebrightening
  12. Konus-Wind detection of GRB 241025A
  13. Fermi trigger No 749693019: Global MASTER-Net observations report
  14. GRB 240821A: Fermi GBM Observation
  15. GRB 240805B: Swift/UVOT Upper Limits
  16. LIGO/Virgo/KAGRA S240615dg: Identification of a GW compact binary merger candidate
  17. GRB 240606B: Fermi GBM Observation
  18. GRB 240513A: AstroSat CZTI detection
  19. Fermi GRB 240428A: Global MASTER-Net observations report
  20. GRB 231215A : MITSuME Akeno optical afterglow candidate detection
  21. GRB 231129C: Swift/BAT-GUANO localization of a burst outside the coded FOV
  22. GRB 231111A: Swift detection of a burst with an optical counterpart
  23. Fermi GRB 231030B: Global MASTER-Net observations report
  24. GRB 230204B: Fermi GBM detection
  25. GRB 230102A: Fermi GBM Observation
  26. GRB221009A: Gemini-South Optical Afterglow Detection
  27. GRB 220803A: AstroSat CZTI detection
  28. IceCube Alert 220513.97: Global MASTER-Net observations report
  29. GRB 220308B: Fermi GBM detection
  30. Fermi GRB 220309A: Global MASTER-Net observations report
  31. IceCube Alert 220202.49: Global MASTER-Net observations report
  32. Fermi GRB 211212A: Global MASTER-Net observations report
  33. Fermi trigger No 653093506: Global MASTER-Net observations report
  34. Konus-Wind detection of GRB 210619B
  35. Fermi trigger No 645047470: Global MASTER-Net observations report
  36. ZTF21aayokph (AT2021lfa): Redshift from Gemini South
  37. Fermi trigger No 641601187: Global MASTER-Net observations report
  38. GRB 210102B: MAXI/GSC detection
  39. GRB 201026A: Swift/UVOT Upper Limits
  40. GRB 201006A: Swift/UVOT Upper Limits
  41. Fermi GRB 200909A: Global MASTER-Net observations report
  42. Fermi GRB 200420A: Global MASTER-Net observations report
  43. LIGO/Virgo S200114f: Gemini Spectra of AT 2020vu, AT 2020vw, AT 2020vy, and AT 2020vz
  44. Fermi trigger No 600666048: Global MASTER-Net observations report
  45. Swift GRB191226.02: Global MASTER-Net observations report
  46. LIGO/Virgo S190814bv Global MASTER-Net observations report
  47. HAWC-190806A: upper limits from INTEGRAL SPI-ACS and IBIS prompt observation
  48. LIGO/Virgo S190602aq: Identification of a GW compact binary merger candidate
  49. GRB 190311A: Swift/UVOT Detection
  50. GRB 171205A: Swift-XRT refined Analysis
  51. GRB 170921A: Swift-XRT refined Analysis
  52. Konus-Wind observation of GRB 170808B
  53. GRB 170803A: Swift/UVOT Detection
  54. GRB 161219B: Swift-XRT refined Analysis
  55. GRB 161213A: POLAR Observation
  56. GRB 160525B: Swift/UVOT Detection
  57. GRB 150831A: Swift/UVOT Upper Limits
  58. Swift Trigger 646423 is GS 1354-645
  59. GRB 150530A: Swift/UVOT Upper Limits
  60. Konus-Wind observation of GRB 140329A
  61. GRB 140311A: Swift/UVOT Upper Limits
  62. GRB 130427A: Zadko observatory - Gingin optical observations
  63. GRB 110213A: Swift/UVOT refined analysis
  64. Konus-Wind observation of GRB 110205A
  65. Short GRB 110106A: MASTER OT observations
  66. GRB 101017A: Swift/UVOT Observations
  67. GRB 100802A: Swift/UVOT Possible Optical Afterglow
  68. GRB100425A: Swift/UVOT Upper Limits
  69. INTEGRAL Alert n. 5995: MASTER-Net optical observations
  70. Swift/UVOT refined analysis of GRB100117A
  71. GRB 091128: Fermi GBM detection
  72. GRB 090904B: Fermi GBM detection
  73. GRB 090815B: Fermi GBM detection
  74. GRB 090423: Fermi GBM observation
  75. Fermi Detection of GRB 081102
  76. GRB080913: Swift/UVOT Upper Limits
  77. GRB 071117: Gemini Observations
  78. Swift/UVOT refined analysis of GRB070531
  79. Konus-Wind observation of GRB 051008
  80. GRB050922B: Swift UVOT early upper limits.
  81. GRB050801: Swift/UVOT Optical and UV detections
  82. Swift/UVOT photometry of GRB050730
  83. ROTSE-III prompt optical detections of GRB 030418
  84. GRB000926 Host Galaxy Observations

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