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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"

2405 results found.

  1. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  2. GRB 260731A: AstroSat CZTI detection of a long burst
  3. GRB 260730B: NuSTAR detection of prompt emission
  4. GRB 260727A: SVOM/ECLAIRs refined analysis
  5. GRB 260726A: SVOM/ECLAIRs refined analysis
  6. GRB 260727A: AbAO and SAO RAS optical observations
  7. GRB 260726A: EP-FXT follow-up observations
  8. GRB 260727A: SVOM/GRM observation
  9. GRB 260726A: Fermi GBM Observation
  10. Konus-Wind detection of GRB 260727A
  11. GRB 260727A: Liverpool Telescope optical upper limits
  12. GRB 260727A: EP/FXT follow-up observations
  13. GRB 260727A: Glowbug gamma-ray detection
  14. GRB 260726A: J-band upper limit with WINTER
  15. GRB 260727A: J-band upper limit with WINTER
  16. GRB 260726A: SVOM/VT optical candidate
  17. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  18. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  19. EP260723a: SVOM/ECLAIRs Upper Limit
  20. GRB 260727A: GOTO early optical upper limit
  21. GRB 260727A: AstroSat CZTI detection
  22. GRB 260727A: Kilonova-Catcher optical upper limit
  23. GRB 260727A: LCO optical upper limits
  24. GRB 260727A: SVOM detection of a bright long burst
  25. GRB 260726A: SVOM detection of a burst
  26. EP260723a: further EP-FXT follow-up observation
  27. GRB 260616A: cubesat Avion detection
  28. GRB 260601A: cubesat Avion detection
  29. EP260723a: EP-FXT follow-up observation
  30. GRB 260718A: SVOM/ECLAIRs refined analysis
  31. EP260723a: SVOM/VT optical observation
  32. Konus-Wind detection of GRB 260714B
  33. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  34. GRB 260714B: Insight-HXMT/HE detection
  35. GRB 260718A: EP-FXT follow-up observation
  36. GRB 260718A: LCO optical upper limits
  37. GRB 260711A: SVOM/GRM observation
  38. GRB 260710A: SVOM/GRM observation
  39. GRB 260718A: Fermi GBM Observation
  40. GRB 260718A : GRANDMA and KNC upper limits
  41. GRB 260718A: SVOM/VT optical upper limits
  42. GRB 260718A: SVOM/VT optical upper limits from VHF data
  43. GRB 260718A: SVOM detection of a burst
  44. GRB 260714B: SVOM/GRM observation
  45. GRB 260618B: EP-FXT follow-up observation upper limit
  46. SVOM sb26071506: Global MASTER-Net observations report
  47. sb26071506: SVOM detection of a X-ray transient
  48. EP260703a: SVOM/ECLAIRs Upper Limit
  49. GRB 260709A: AstroSat CZTI detection
  50. GRB 260706A: ATCA detection of possible radio counterpart
  51. GRB 260705A: ATCA radio observations
  52. GRB 260619A: SVOM/VT continuous optical observations
  53. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  54. GRB 260708A: GRANDMA Optical Observations
  55. GRB 260708A: LCO optical observations
  56. GRB 260709A: SVOM/GRM detection
  57. GRB 260704A: SVOM/ECLAIRs refined analysis
  58. GRB 260706A : GRANDMA Upper limits
  59. GRB 260705B: SVOM/GRM observation
  60. GRB 260706A: Further EP-FXT follow-up observation
  61. GRB 260706A: SVOM/VT optical upper limits
  62. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  63. GRB 260706A: SVOM/ECLAIRs refined analysis
  64. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  65. GRB 260706A: SVOM/GRM observation
  66. GRB 260706A: REM optical/NIR observations
  67. GRB 260706A: LCO optical upper limit
  68. GRB 260706A: EP-FXT follow-up observation
  69. GRB 260706A: Fermi GBM Observation
  70. GRB 260705A: SVOM/ECLAIRs refined analysis
  71. GRB 260706A: SVOM detection of a burst
  72. GRB 260705A: LCO optical upper limits
  73. GRB 260704A: NOT optical upper limits
  74. Fermi GBM Sub-Threshold Detection of GRB 260705A
  75. GRB 260705A: SVOM detection of a burst
  76. GRB 260704A: EP-FXT follow-up observation
  77. GRB 260629A: SVOM/GRM observation of a short burst
  78. GRB 260704A: SVOM detection of a possible GRB
  79. GRB 260614B: ATCA Radio Upper Limits
  80. MASS-Cube (GRID 2.0) detection of GRB 260616B
  81. GRB 260619A: SVOM/ECLAIRs refined analysis
  82. IPN triangulation of GRB 260605A
  83. EP260623a: SVOM/VT optical observations
  84. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  85. GRB 260614B: EP-FXT follow-up observation
  86. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  87. GRB 260619A: NOT optical observations
  88. GRB 260618B: LCO optical observations
  89. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  90. GRB 260618B: Fermi GBM Observation
  91. GRB 260619A: TRT optical counterpart confirmation
  92. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  93. GRB 260604B: 239Alferov CubeSat detection
  94. GRB 260604A: 239Alferov CubeSat detection
  95. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  96. GRB 260619A: SVOM/VT optical counterpart confirmation
  97. GRB 260618B: SVOM/VT optical candidate
  98. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  99. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  100. GRB 260616A: SVOM/GRM observation

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