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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"

16272 results found.

  1. GRB 210217A: NEXT early optical afterglow observations
  2. GRB 210212A: Mondy optical observations
  3. GRB 210217A: Swift detection of a burst with an optical counterpart
  4. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued Assy and Mondy optical observations
  5. IceCube-210210A: Two Additional Optical Candidate Counterparts Found by DECam
  6. GRB 210208A: 1.3m DFOT Optical upper limit
  7. GRB 210211A: ePESSTO+ NTT optical observations
  8. GRB 210212B (TF21aakruew/AT2021cwd): Assy optical observations
  9. IPN triangulation of GRB 210212B (consistent with ZTF21aakruew/AT2021cwd)
  10. GRB 210212A: 1.3m DFOT Optical upper limit
  11. ZTF21aakruew/AT2021cwd: ZTF and LT discovery of a hostless, red, and rapidly fading optical transient
  12. GRB 210212A: Gemini South optical observations
  13. GRB 210210A: CAHA 2nd epoch and jet break confirmation
  14. IceCube-210210A: Four Candidate Optical Counterparts from DECam Observations
  15. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued CrAO and AbAO optical observations
  16. GRB 210212A: Possible host galaxy counterpart with the NOT
  17. GRB 210212A: MITSuME Akeno optical upper limits
  18. GRB 210212A: BOOTES-4/MET optical upper limit
  19. GRB 210212A: Swift/UVOT Upper Limits
  20. GRB 210204A: observations with the 3.6m Devasthal Optical Telescope and possible jet break
  21. GRB 210210A : 1.3m DFOT optical observations
  22. GRB 210210A as a BdHN II
  23. Swift-XRT observations of IceCube-210210A
  24. GRB 210211A: MASTER optical observation of REM OT
  25. GRB 210210A: CAHA detection and likely jet break
  26. GRB 210211A: REM optical/NIR afterglow detection
  27. GRB 210210A: FRAM-ORM afterglow detection
  28. GRB 210209A: BOOTES-4/MET optical upper limit
  29. GRB 210210A: LCO Optical Afterglow Detection
  30. GRB 210209A: MITSuME Akeno optical upper limits
  31. GRB 210209A: Swift/UVOT Upper Limits
  32. GRB 210208A: GIT optical upper limit
  33. GRB 210210A: MASTER afterglow observation
  34. ZTF21aahifke/AT2021clk: ZTF discovery of an optical fast transient (possible afterglow)
  35. GRB 210210A: Swift detection of a burst with an optical counterpart
  36. GRB 210207B: Continued LCO Observations
  37. GRB 210208A: BOOTES-2/TELMA optical upper limit
  38. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued Mondy optical observations
  39. GRB 210207B: LCO Optical Afterglow Detection
  40. GRB 210207B: KAIT Optical Observations
  41. GRB 210207B: AbAO optical upper limit
  42. GRB 210207B: optical detection with 3.6m Devasthal Optical Telescope
  43. GRB 210207B: Swift detection of a burst with a bright optical counterpart
  44. GRB 210204A (ZTF21aagwbjr/AT2021buv): Mondy and AbAO optical observations
  45. Konus-Wind detection of GRB 210204A / ZTF21aagwbjr
  46. GRB 210204A: Optical Observations from HCT
  47. VLT/X-shooter redshift of 1.466 for ZTF21aagwbjr/AT2021buv, strengthening its association with GRB 210204A
  48. IPN triangulation of GRB 210204A
  49. GRB 210205A: MITSuME Ishigaki optical observation
  50. ZTF21aagwbjr/AT2021buv: ZTF discovery of a fast optical transient likely associated with GRB 210104A
  51. GRB 210205A: Swift/UVOT Upper Limits
  52. GRB 210205A: Nanshan/NEXT optical upper limit
  53. GRB 210205A: BOOTES-4/MET optical upper limit
  54. GRB 210205A： GWAC-F60A optical upper limit
  55. Continued Chandra observations of GW170817 at ~3.3 years since merger
  56. ZTF21aaeyldq: Observations with the 3.6m DOT
  57. GRB 210120A: Fermi GBM detection
  58. GRB 210120A : 1.3m DFOT optical observations
  59. ZTF20aaeyldq: VLA radio detection
  60. GRB 210120A(MASTER OT J105242.66+152355.0 / AT2021axc): Mondy optical observations
  61. GRB 210120A: MASTER OT (possibly) discovery
  62. GRB 210104A: 3.6m DOT optical upper limit
  63. GRB 210112A: 3.6m DOT optical detection
  64. GRB 200613A: Host galaxy redshift from OSIRIS/GTC
  65. ZTF21aaeyldq (AT2021any): Detection of X-ray Emission with Swift/XRT
  66. ZTF21aaeyldq: 2.2m CAHA BVRI optical observations
  67. GRB 201221D: near-infrared observation with LBT
  68. ZTF21aaeyldq: NOT optical observations
  69. ZTF21aaeyldq: observations with the 3.6m Devasthal Optical Telescope
  70. ZTF21aaeyldq: GTC Redshift and GRB afterglow nature confirmation
  71. ZTF Discovery of ZTF21aaeyldq (AT2021any): a Hostless, Young, and Rapidly Fading Transient
  72. GRB 210112A: Mondy optical observations
  73. GRB 210112A: 1.3m DFOT Optical upper limit
  74. GRB 210112A: OSN second epoch, decay
  75. GRB 210112A: OSN Reddened Afterglow Detection
  76. GRB 210112A: Kitab a optical upper limit
  77. GRB 210104A: AROMA-N Optical Afterglow Detection
  78. GRB 210112A: Swift detection of a burst with an optical counterpart
  79. GRB 210104A: Mondy optical observations, light curve
  80. GRB 210104A: Assy continued optical observations, correction to GCN circ. 29265
  81. GRB 201227A: continued Chilescope confirmation of variability of possible optical counterpart, redshift estimating
  82. GRB 210104A: SAO RAS optical observations
  83. GRB 210104A: GMG observations
  84. GRB210104A: VIRT optical transient detection.
  85. GRB 210104A: SARA-KP 0.9m Optical Afterglow Detection
  86. GRB 210102B: further Swift-XRT observations
  87. GRB 210102B: Assy optical afterglow identification
  88. GRB 210104A: iTelescope optical upper limit
  89. GRB 210104A: Assy continued optical observations
  90. GW170817: HST observations at 3.4 years from merger
  91. GRB 210104A: early ATLAS detections of the bright afterglow
  92. GRB 210104B: Swift/UVOT Upper Limits
  93. GRB 210104A: 1.3m DFOT Optical Afterglow Detection
  94. GRB 210104B: Assy optical upper limit
  95. GRB 210104A: DOAO optical afterglow observations
  96. GRB 210104A: Nanshan/NEXT optical powerlaw decay
  97. GRB 210104B: Nanshan/NEXT optical upper limit
  98. GRB 210104B: BOOTES network optical upper limit
  99. GRB 210104A: MITSuME Ishigaki optical observation
  100. GRB 210102B: Assy optical observations

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