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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_MC170616_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"

10919 results found.

  1. GRB 260925A: Swift/UVOT Upper Limits
  2. GRB 260924A: Optical follow-up observations with Kinder
  3. GRB 260924A: Swift/UVOT Detection
  4. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  5. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  6. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  7. GRB 260917B:: SVOM/ECLAIRs refined analysis
  8. EP260920a: VLT/HAWK-I near-infrared candidate
  9. GRB 260921A: Swift detection of a burst
  10. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  11. EP260920b: SVOM/VT optical observation
  12. EP260920a: NOT early time optical upper limits
  13. EP260920a: SVOM/VT optical upper limits
  14. GRB 260915A: VLT optical and near-infrared upper limits
  15. EP260917a: SVOM/VT optical upper limits
  16. GRB 260918A: SVOM/VT optical upper limits
  17. GRB 260917B: Mondy optical upper limit
  18. GRB 260917B: SVOM/VT optical observations
  19. GRB 260914A: Mondy and TShAO optical observations
  20. GRB 260914A: SVOM/ECLAIRs refined analysis
  21. GRB 260916A: MAXI/GSC detection
  22. GRB 260915A: SVOM/VT refined early optical upper limits
  23. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  24. GRB 260915A: SVOM/VT optical upper limits
  25. GRB 260915A: SVOM/VT optical upper limits from VHF data
  26. GRB 260915A: LCO optical upper limits
  27. GRB 260915A: SVOM detection of a burst
  28. GRB 260914A: SVOM/VT optical counterpart confirmation
  29. GRB 260914A: SVOM detection of a burst
  30. GRB 260818A: Continued ATCA observations
  31. GRB 260909A: CrAO and AbAO optical upper limits
  32. GRB 260909A: VLT optical and near-infrared upper limits
  33. GRB 260909A: EP-FXT follow-up observation
  34. GRB 260909A: SVOM/VT optical upper limits
  35. GRB 260909A: Mondy optical observations and afterglow candidate
  36. GRB 260909A: Xinglong 2.16m optical upper limit
  37. GRB 260903A: SAO RAS optical upper limit
  38. EP260903a: EP-FXT follow-up observation
  39. GRB 260903A: SAO RAS optical observations
  40. GRB 260903A: SVOM/VT optical candidate
  41. EP260901a: SVOM/VT optical upper limits
  42. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  43. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  44. GRB 260808B: SAO RAS observations of the optical rebrightening
  45. GRB 260822A: SVOM/VT optical upper limits
  46. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  47. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  48. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  49. EP260806a: SAO RAS multicolor optical observations
  50. EP260812a: AbAO optical upper limit
  51. EP260812b: Optical upper limit with Kinder
  52. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  53. EP260812b: SVOM/VT optical observation
  54. GRB 260809A: SAO RAS optical observations
  55. GRB 260808B: SAO RAS optical observations
  56. GRB 260808B: SVOM/VT optical re-brightening at day 3
  57. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  58. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  59. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  60. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  61. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  62. GRB 260809A: SVOM/VT optical counterpart
  63. GRB 260808B: SVOM/VT optical afterglow confirmation
  64. EP260806a: SVOM/VT optical observation
  65. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  66. EP260806a: OSIRIS+/GTC redshift z=0.089
  67. GRB 260715A: cubesat Avion detection
  68. GRB 260708A: cubesat Avion detection
  69. SN 2026stf / GRB 260708A: ATLAS forced photometry
  70. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  71. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  72. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  73. EP260727a: SAO RAS optical observations
  74. GRB 260727A: AbAO and SAO RAS optical observations
  75. GRB 260726A: SVOM/VT optical candidate
  76. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  77. GRB 260616A: cubesat Avion detection
  78. GRB 260602B: cubesat Avion detection
  79. GRB 260601A: cubesat Avion detection
  80. EP260723a: EP-FXT follow-up observation
  81. EP260723a: SVOM/VT optical observation
  82. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  83. GRB 260718A : GRANDMA and KNC upper limits
  84. GRB 260718A: SVOM/VT optical upper limits
  85. GRB 260718A: SVOM/VT optical upper limits from VHF data
  86. GRB 260618B: EP-FXT follow-up observation upper limit
  87. GRB 260714B: Fermi-LAT detection
  88. GRB 260619A: SVOM/VT continuous optical observations
  89. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  90. GRB260708B: MAXI/GSC detection
  91. GRB 260706A: SVOM/VT optical upper limits
  92. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  93. GRB 260705A: SVOM/ECLAIRs refined analysis
  94. GRB 260705A: SVOM detection of a burst
  95. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  96. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  97. EP260628a: EP-FXT follow-up observation
  98. EP260628a: EP-WXT detection of a fast X-ray transient
  99. GRB 260619A: SVOM/ECLAIRs refined analysis
  100. EP260623a: Optical follow-up observations with Kinder

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