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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

16156 results found.

  1. GRB 210504A: LCO Optical Afterglow Detection
  2. GRB 210514A: Swift/UVOT Upper Limits
  3. GRB210510A: Optical afterglow candidate from the Zwicky Transient Facility
  4. Short GRB 210323A: likely host galaxy detection
  5. GRB 210509A: RATIR Optical and NIR Upper Limits
  6. GRB 210509A: Swift/UVOT Upper Limits
  7. GRB 210509A: BOOTES-4/MET optical upper limit
  8. ZTF21aayokph (AT2021lfa): continued Mondy optical observations
  9. ZTF21aayokph (AT2021lfa): MASTER OT detection 3h befor ZTF
  10. GRB 210506A: Nanshan/NEXT optical upper limit
  11. ZTF21aayokph (AT2021lfa): Mondy and Koshka observatory optical observations
  12. ZTF21aayokph (AT2021lfa): Assy optical observations
  13. ZTF21aayokph (AT2021lfa): Nanshan/NEXT optical upper limit
  14. GRB 210504A: Lowell Discovery Telescope optical observations
  15. GRB 210504A: VLT X-shooter redshift
  16. GRB 210504A: NOT optical afterglow detection
  17. GRB 210504A: MITSuME Akeno optical upper limits
  18. GRB 210504A: AST3-3 YaoAn Optical Upper Limit
  19. GRB 210504A: BOOTES-4/MET optical upper limit
  20. Swift Detection of MAXI J1803-298 including an optical counterpart
  21. GRB 210430A: BOOTES-1 optical limit
  22. GRB 210424B: MITSuME Akeno optical upper limits
  23. GRB 210420B: Assy optical observations
  24. GRB 210420B: follow-up photometry of optical afterglow at INASAN/Simeiz
  25. GRB 210420B: Zeiss-1000 of Koshka optical observations
  26. GRB 210421A: Swift/UVOT Upper Limits
  27. GRB 210420B: follow-up photometry of the optical afterglow at Konkoly
  28. GRB 210421A: MITSuME Akeno optical upper limits
  29. GRB 210419C: Swift/UVOT Upper Limits
  30. GRB 210420B: Ondrejov D50 optical afterglow detection
  31. GRB 210420B: RATIR Optical and NIR Observations
  32. GRB 210420B: Swift/UVOT Detection
  33. GRB 210420B: KAIT Optical Observations
  34. GRB 210413B: MITSuME Okayama optical upper limits
  35. GRB 210419C: MITSuME Akeno optical upper limits
  36. GRB 210420B: Multiband photometry from NOT
  37. GRB 210420B: Montarrenti Observatory optical afterglow detection
  38. GRB 210420B: AST3-3 YaoAn Optical Observation
  39. GRB 210420B: BOOTES-4/MET optical afterglow detection
  40. GRB 210420B: Optical observations
  41. GRB 210420B: MASTER optical counterpart detection
  42. GRB 210419C: RATIR Optical and NIR Upper Limits
  43. GRB 210419C: Montarrenti Observatory Upper Limit
  44. GRB 210419A: Swift/UVOT Upper Limits
  45. GRB 210419C: KAIT Optical Upper Limit
  46. GRB 210419A: LCO Optical Upper Limit
  47. GRB 210413B: LOAO optical upper limit
  48. IceCubeCascade-210416a: Kanata Optical Imaging of 3C 279
  49. GRB 210411C: Chilescope optical observations
  50. GRB 210411C: ePESSTO+ NTT optical observations
  51. GRB 210411C: VLT/X-shooter redshift
  52. GRB 210410A: MITSuME Akeno optical upper limits
  53. GRB 210411C: BOOTES-4/MET optical upper limit
  54. GRB 210411C: LCO Optical Afterglow Candidate
  55. GRB 210406A: 10.4m GTC follow-up observation
  56. GRB 210411C: Swift detection of a burst with an optical counterpart
  57. GRB 210410A: Swift/UVOT Upper Limits
  58. GRB210410A: Joint inspection of RATIR and D50 data
  59. GRB 210406A: Swift-XRT observations
  60. GRB 210410A: RATIR Optical and NIR Observations
  61. GRB210410A: Candidate optical afterglow by Ondrejov D50
  62. GRB 210406A: Mondy optical afterglow candidate
  63. GRB 210406A: Mondy optical upper limit
  64. GRB 210406A: Konkoly Obs. optical upper limit
  65. GRB 210406A: BOOTES-4/MET optical upper limit
  66. GRB 210402A: MASTER prompt and follow up optical observation
  67. GRB 210402A: Swift/UVOT Upper Limits
  68. GRB 210402A: Further NOT optical observations
  69. GRB 210207B: Prompt and very late time observations with HCT.
  70. GRB 210402A: NOT optical afterglow candidate
  71. GRB 210402A: BOOTES-network early optical upper limit
  72. GRB 210402A: Montarrenti Observatory upper limit
  73. GRB 210402A: NOT optical upper limits
  74. GRB 210330A: MASTER optical observation
  75. GRB 210321A: OSN Upper Limit
  76. GRB 210323A: MASTER optical observation
  77. GRB 210323A: Gemini-North Optical Source Detection
  78. GRB 210312B: OSN Afterglow Observations
  79. GRB 210323A: Swift/UVOT Upper Limits
  80. GRB 210323A: Kitab optical upper limit
  81. GRB 210323A: Mondy optical observations, counterpart detection
  82. GRB 210318A: Swift/UVOT Upper Limits
  83. GRB 210323A: NOT optical afterglow candidate
  84. GRB 210323A: Nanshan/NEXT optical upper limit
  85. GRB 210318B: Swift/UVOT Upper Limits
  86. GRB 210321A: CrAO optical upper limit
  87. GRB 210321A: Mondy optical observations
  88. GRB 210321A: Xinglong GWAC-F60A optical observation
  89. GRB 210321A: NOT optical afterglow detection and redshift limit
  90. GRB 210321A: MASTER optical observation
  91. GRB 210318B: MITSuME Okayama optical upper limits
  92. GRB 201216C: VIRT optical observations
  93. GRB 210306A: GIT optical follow-up
  94. GRB 210226A: GIT optical upper limit
  95. GRB 210306A: HCT optical upper limit
  96. GRB 210312B: MASTER OT confirmation
  97. GRB210312B (Integral alert 9073): Candidate optical afterglow by Ondrejov D50
  98. GRB 210306A: Tautenburg observations
  99. GRB 171205A: Continued ATCA observations
  100. GRB 210306A: Early Spectroscopy of the Optical Afterglow

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