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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.

"N/A_MC161217_R1" does not adhere to advanced search syntax. Please refer to the documentation and try again.
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"

10877 results found.

  1. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  2. GRB 260808B: SAO RAS observations of the optical rebrightening
  3. GRB 260822A: SVOM/VT optical upper limits
  4. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  5. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  6. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  7. EP260806a: SAO RAS multicolor optical observations
  8. EP260812a: AbAO optical upper limit
  9. EP260812b: Optical upper limit with Kinder
  10. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  11. EP260812b: SVOM/VT optical observation
  12. GRB 260809A: SAO RAS optical observations
  13. GRB 260808B: SAO RAS optical observations
  14. GRB 260808B: SVOM/VT optical re-brightening at day 3
  15. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  16. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  17. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  18. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  19. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  20. GRB 260809A: SVOM/VT optical counterpart
  21. GRB 260808B: SVOM/VT optical afterglow confirmation
  22. EP260806a: SVOM/VT optical observation
  23. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  24. EP260806a: OSIRIS+/GTC redshift z=0.089
  25. GRB 260715A: cubesat Avion detection
  26. GRB 260708A: cubesat Avion detection
  27. SN 2026stf / GRB 260708A: ATLAS forced photometry
  28. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  29. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  30. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  31. EP260727a: SAO RAS optical observations
  32. GRB 260727A: AbAO and SAO RAS optical observations
  33. GRB 260726A: SVOM/VT optical candidate
  34. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  35. GRB 260616A: cubesat Avion detection
  36. GRB 260602B: cubesat Avion detection
  37. GRB 260601A: cubesat Avion detection
  38. EP260723a: EP-FXT follow-up observation
  39. EP260723a: SVOM/VT optical observation
  40. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  41. GRB 260718A : GRANDMA and KNC upper limits
  42. GRB 260718A: SVOM/VT optical upper limits
  43. GRB 260718A: SVOM/VT optical upper limits from VHF data
  44. GRB 260618B: EP-FXT follow-up observation upper limit
  45. GRB 260714B: Fermi-LAT detection
  46. GRB 260619A: SVOM/VT continuous optical observations
  47. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  48. GRB260708B: MAXI/GSC detection
  49. GRB 260706A: SVOM/VT optical upper limits
  50. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  51. GRB 260705A: SVOM/ECLAIRs refined analysis
  52. GRB 260705A: SVOM detection of a burst
  53. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  54. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  55. EP260628a: EP-FXT follow-up observation
  56. EP260628a: EP-WXT detection of a fast X-ray transient
  57. GRB 260619A: SVOM/ECLAIRs refined analysis
  58. EP260623a: Optical follow-up observations with Kinder
  59. EP260623a: SVOM/VT optical observations
  60. EP260623a: OSIRIS+/GTC redshift z = 0.703
  61. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  62. GRB 260619A: SVOM/VT optical counterpart confirmation
  63. GRB 260618B: SVOM/VT optical candidate
  64. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  65. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  66. GRB 260618B: Fermi-LAT detection
  67. GRB 260610B: AbAO optical observations
  68. GRB 260506B: cubesat Avion detection
  69. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  70. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  71. GRB 260429A: cubesat Avion detection
  72. GRB260616C: MAXI/GSC detection
  73. GRB 260616A: Fermi-LAT detection
  74. GRB 260610B: Terskol optical observations
  75. GRB 260614B: SVOM/VT optical afterglow confirmation
  76. GRB 260610B / AT2026owq: GRANDMA optical observations
  77. GRB 260610B / AT2026owq: further SAO RAS optical observations
  78. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  79. GRB 260610B / AT2026owq: SVOM/VT optical observations
  80. GRB 260610B: IAC-80 Optical observations
  81. GRB 260610B / AT2026owq: SAO RAS optical observations
  82. GRB 260610B / AT2026owq: Early ATLAS observations
  83. EP260610b: SVOM/VT optical confirmation with blue color
  84. EP260610b: Gemini North optical counterpart candidate
  85. EP260610a: SVOM/VT optical upper limits
  86. IPN triangulation of GRB 260601A (short/hard)
  87. IPN triangulation of GRB 260601B / EP260601a
  88. GRB 260604C: SVOM/ECLAIRs refined analysis
  89. GRB 260604C: further SAO RAS optical observations
  90. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  91. GRB 260604C: SVOM/C-GFT upper limit
  92. GRB 260604C: GRANDMA further observations
  93. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  94. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  95. GRB 260607B: Fermi-LAT detection
  96. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  97. GRB 260604C: SAO RAS optical observations
  98. GRB 260604C: GRANDMA observations
  99. GRB260603A: SVOM/ECLAIRs refined analysis
  100. GRB 260604C: SVOM detection of a long burst

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