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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_MC151116_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"

10892 results found.

  1. GRB 260914A: SVOM/VT optical counterpart confirmation
  2. GRB 260914A: SVOM detection of a burst
  3. GRB 260818A: Continued ATCA observations
  4. GRB 260909A: CrAO and AbAO optical upper limits
  5. GRB 260909A: VLT optical and near-infrared upper limits
  6. GRB 260909A: EP-FXT follow-up observation
  7. GRB 260909A: SVOM/VT optical upper limits
  8. GRB 260909A: Mondy optical observations and afterglow candidate
  9. GRB 260909A: Xinglong 2.16m optical upper limit
  10. GRB 260903A: SAO RAS optical upper limit
  11. EP260903a: EP-FXT follow-up observation
  12. GRB 260903A: SAO RAS optical observations
  13. GRB 260903A: SVOM/VT optical candidate
  14. EP260901a: SVOM/VT optical upper limits
  15. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  16. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  17. GRB 260808B: SAO RAS observations of the optical rebrightening
  18. GRB 260822A: SVOM/VT optical upper limits
  19. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  20. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  21. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  22. EP260806a: SAO RAS multicolor optical observations
  23. EP260812a: AbAO optical upper limit
  24. EP260812b: Optical upper limit with Kinder
  25. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  26. EP260812b: SVOM/VT optical observation
  27. GRB 260809A: SAO RAS optical observations
  28. GRB 260808B: SAO RAS optical observations
  29. GRB 260808B: SVOM/VT optical re-brightening at day 3
  30. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  31. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  32. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  33. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  34. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  35. GRB 260809A: SVOM/VT optical counterpart
  36. GRB 260808B: SVOM/VT optical afterglow confirmation
  37. EP260806a: SVOM/VT optical observation
  38. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  39. EP260806a: OSIRIS+/GTC redshift z=0.089
  40. GRB 260715A: cubesat Avion detection
  41. GRB 260708A: cubesat Avion detection
  42. SN 2026stf / GRB 260708A: ATLAS forced photometry
  43. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  44. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  45. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  46. EP260727a: SAO RAS optical observations
  47. GRB 260727A: AbAO and SAO RAS optical observations
  48. GRB 260726A: SVOM/VT optical candidate
  49. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  50. GRB 260616A: cubesat Avion detection
  51. GRB 260602B: cubesat Avion detection
  52. GRB 260601A: cubesat Avion detection
  53. EP260723a: EP-FXT follow-up observation
  54. EP260723a: SVOM/VT optical observation
  55. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  56. GRB 260718A : GRANDMA and KNC upper limits
  57. GRB 260718A: SVOM/VT optical upper limits
  58. GRB 260718A: SVOM/VT optical upper limits from VHF data
  59. GRB 260618B: EP-FXT follow-up observation upper limit
  60. GRB 260714B: Fermi-LAT detection
  61. GRB 260619A: SVOM/VT continuous optical observations
  62. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  63. GRB260708B: MAXI/GSC detection
  64. GRB 260706A: SVOM/VT optical upper limits
  65. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  66. GRB 260705A: SVOM/ECLAIRs refined analysis
  67. GRB 260705A: SVOM detection of a burst
  68. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  69. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  70. EP260628a: EP-FXT follow-up observation
  71. EP260628a: EP-WXT detection of a fast X-ray transient
  72. GRB 260619A: SVOM/ECLAIRs refined analysis
  73. EP260623a: Optical follow-up observations with Kinder
  74. EP260623a: SVOM/VT optical observations
  75. EP260623a: OSIRIS+/GTC redshift z = 0.703
  76. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  77. GRB 260619A: SVOM/VT optical counterpart confirmation
  78. GRB 260618B: SVOM/VT optical candidate
  79. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  80. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  81. GRB 260618B: Fermi-LAT detection
  82. GRB 260610B: AbAO optical observations
  83. GRB 260506B: cubesat Avion detection
  84. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  85. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  86. GRB 260429A: cubesat Avion detection
  87. GRB260616C: MAXI/GSC detection
  88. GRB 260616A: Fermi-LAT detection
  89. GRB 260610B: Terskol optical observations
  90. GRB 260614B: SVOM/VT optical afterglow confirmation
  91. GRB 260610B / AT2026owq: GRANDMA optical observations
  92. GRB 260610B / AT2026owq: further SAO RAS optical observations
  93. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  94. GRB 260610B / AT2026owq: SVOM/VT optical observations
  95. GRB 260610B: IAC-80 Optical observations
  96. GRB 260610B / AT2026owq: SAO RAS optical observations
  97. GRB 260610B / AT2026owq: Early ATLAS observations
  98. EP260610b: SVOM/VT optical confirmation with blue color
  99. EP260610b: Gemini North optical counterpart candidate
  100. EP260610a: SVOM/VT optical upper limits

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